People who don't capitalize their I's

Then there are those who are too lazy to capitalize anything, and, in addition to the drastic grammatical transgression that I describe here, also like to use the (lowercase!) letter "u" in place of the word "you".

You cannot spend more than a few days online (unless you only look at business webpages designed by people who are paid to have good grammar) without running into some variation on these two basic personality types. They are a necessary and necessarily annoying part of any online community.

IMHO, those conventions are handy. Anytime I see that big I thing, I recognize it immediately.
Anyway, it is not a holy matter: one could as well start writing "y" instead of "and" - it is much shorter, isn't it ? So let us not look for bullshit reasons like "Ooooh, the Shift key is so terribly far from my little fingers on this big keyboard".
I mean, one could as well drop punctuation ... - it boils down to attitude. You don't capitalize that pronoun? The message that comes across is that you don't give a damn about other people's reading convenience. And perhaps, you are so convinced of the excellence of your thoughts that you do not even try to package them well.

This is of course a dangerous attitude, as many corporate web site designers have discovered.

Language is not a place for you to express your individualism. We have more media for that than it is convenient for me to describe here. Language is standardized for a reason. Way back when, it had to be standardized or there'd be errors in communication. Errrors in communication meant lost opportunities, inconvenience, and worse. This sentiment has survived to this day. If you're not using the widely accepted "correct" form the language, then you're making it harder for others to read your English. Years of reading have instilled in me the reflex to equate a lone capital "I" with a referece by the writer to himself or herself. If you refuse to capitalize "I", it takes a few milliseconds longer for my cognitive responses to analyze your sentence. And I've already become minutely exasperated with this inconvenience as a result.

Yes, language does change. But mind you, it's a VERY slow evolution. The median form of any language will not change in, one, two, or even three generations at all. And certainly you, the "rogue capitalizationalists", will not be the ones to exact this change in English grammar. Many people will not even consider this a legitimate stylistic choice. The VAST majority of English speakers accept "I" as "correct", and if they ever lapse, it is only out of laziness. (Which, in my opinion, is hardly a much better excuse. However, those who do this out of laziness still recognize the capital form as being correct.)

It is worth noting, though, that I am not a stickler for capital letters. I am only a stickler for correctness. We can expect a very specific grammatical and syntactical behavior from the English language. Breaking these conventions not only annoy native speakers, but seriously increase the difficulty levied on non-native speakers, who have just as much right to participate in E2 as we do. Mind you, I would not condone the following sentence, in French:

Je veux dormir, parce que Je suis fatigué.

You will get several snickers from the French-speaking crowd if you try and write that. You see, the convention in French would consider it downright wrong to put a capitalized je in the middle of a sentence. French speakers expect it to be all lowercase. So, if you were to type something in French, you'd better not break the conventions of that specific language either, or you'll be making it harder on them. They have their reasons why their language is like that, and we have ours. It is a disrespect to all English speakers when you personally decide the rules which they all follow do not apply to you.

So, in conclusion, you should make a statement with your thoughts and reason, not with the letters you use to express your thoughts and reason. Thank you, have a nice day.