There is always a complaint that Tamils are excessively proud about their language. I agree. It surely doesn't make them superior to others. If your language is older than someone else's or if it has more literature than someone else's, it is just a fact and there is nothing to feel superior about it. You can still feel proud about it, not excessively though. What makes them feel so? They truly believe that their language is an asset for them. The reasons are many. Antiquity of the language, the amount of literature they have preserved, strength of its grammar, vocabulary (though can't be compared with Sanskrit!), the love all their kings and their kingdoms had for it (including the kings that came from outside!), spread of the people that speak the language, their relentless efforts in translating every single scientific/technical term to their language, and more than all that, the simplicity of the language, etc. etc.
Invasion was way of life for a long time. Like everywhere else, there also, a lot of outsiders came, conquered and went. They also looted their wealth, harassed their people and did everything that any invader does. None of them could destroy their language. Everywhere else the language changed. Only there, it didn't happen. I mean, here also, the language changed but not completely. Everywhere else, the name of the language itself changed. New letters came in. New pronunciations came in. New languages were born. Only there, the same language went through change. At the max, only new words were introduced. It's the same letters that were there in the first available literature, which are being used even today. Even the same pronunciations are there today. Even today there are people who name their kids in pure Tamil, which is way different from what we are speaking today. There are many letters that are called Sanskrit letters, which have not been included in Tamil yet. They don't feature in original Tamil letters list. They are just given as supplementary. There are people who are against adding them to Tamil alphabets list for the reason that they won't be able to prove that Tamil is not an offshoot from Sanskrit if they do that. They use those letters only in the borrowed words. Borrowed words? Yes. There is a list of words that they call "borrowed words", which are nothing but the pure Sanskrit words. For every such word, there is an equivalent Tamil word, which just doesn't sound like Sanskrit. But, most of the common men don't know those words. Including the priests that chant mantras in Sanskrit, everyone speaks Tamil so proudly at home.
Like all others, Tamils also go all around the world for their livelihood and learn the languages of the land (Bangaloreans! please excuse here... they don't do that in Bangalore because they feel at home here!). When they do that, people make fun of them for their accent and pronunciations. There are reasons for why that happens. Why they are made fun of? And, why they speak such a funny accent? That is what I want talk about today. Being aware of them helps both the parties (the ones that make fun and the ones that are made fun of) understand each other better. That's it.
OK. Can they not even pronounce the existing letters? Yes. That's the reason why they can't learn other languages so easily. There is only one equivalent letter for all the following five in other Indian languages - KA, KHA, GA, GHA, and HA. All these five names - Kamal, Khaleel, Ganesh, Ghajini, and Hari start with the same letter. It doesn't mean that they pronounce the first letter the same way in all these words. We just have to change the pronunciation based on the context. It's only when people do not know when to change to what, they are made fun of. Many people know the difference in pronunciation but don't know the reason why there are not five letters like in other languages. Let's see that reason today. Another thing before we get into that - only KA in Kamal is a pure Tamil letter; rest all came from Sanskrit or other languages. But, there is something in their grammar, which explains the difference in pronunciation. The same letter that is used for KA in the beginning of a word should become GA or HA when it comes in the middle. So, a pure Tamil word would not have HA or GA as its first letter. It's only the borrowed words that have these letters as the first letter. It's only those people who had poor attendance in elementary school who make mistakes in these pronunciations. :)
On top of all these there is something called compound letters. KKA, CHCHA, TTA, DDA, THTHA, DHDHA, PPA, NKA, NGA, NJA, NDA, NTA, NDHA, NTHA, MPA, MBA, MMA, RRA, LLA, NNA, etc. They are there in Sanskrit as well, but they are handled differently in Tamil and Malayalam. There is no NKA, NTA, NTHA, MPA, etc. They just have to be pronounced NGA, NDA, NDHA, MBA respectively. You are not supposed to stress for the second letter in compound letters - like in NKA, NTA, NTHA, MPA, etc. In some languages, they are written as subscripts, which makes things even tougher. Telugu and Kannada follow this style. Luckily, Tamil does not have this difficulty - in addition to the existing ones! :)
More than all these, there is another very valid complaint. Only Tamils and Malayalis can understand what I am going to talk about. The complain is, more than three fourth of the people that speak this language called 'Tamil' can't even pronounce the word 'Tamil' properly. It's supposed to be pronounced "Thamizh'. This 'ZH' pronunciation easily comes for Malayalis but it's very difficult for most of the Tamils though they boast that their language has three different pronunciation for L. One of them - this 'ZH' thing is not even there in Sanskrit. It is only in Tamil and Malayalam. Whose mistake it is? Don't know! Thanks to the British. It's become stylish to say Tamil instead of Thamizh today, which saves a lot of more embarrassment, especially with Malayalis. :)
I also feel that you should take good things from anyone, irrespective of wherever it comes from, so Tamil also should have adopted the letters that it didn't have as its own and enriched itself. But, there are people who still argue that if we had adopted good things from others, we would have lost the natural beauty of the language and we would be speaking a different language and calling it Damil or Dumil by now. That's the reason why people don't spend so much time in enriching the language with new letters as they do with new words. Maybe because we didn't interact so much with the outside world, we never had to think about it before. Looks like this is the best time to start thinking about it seriously. Don't know who has the answer to this.