timppu: I think all languages where the meaning of the spoken word changes completely due to (wrong) intonation are totally messed up.
Then again, your viewpoint is totally biased. In any case, intonation carries plenty of meaning in Finnish and English as well, although on a syntactic (sentence) level; there is a distinct difference between saying "I am a dog" with a falling or rising intonation, the former indicating declaration of fact, the latter inquiry or uncertainty. Not to mention word stress - RE-cord and re-CORD are completely different things, the former being a noun and the latter a verb.
timppu: Why don't you simply pronounce it as it is written, like we do in Finnish (save for maybe "ng" as in "kengät" (shoes), which is a single special case)? All languages should be written phonetically.
Because people wouldn't pronounce English as it was written but write it as it was spoken. I think you see the problem if you consider the number of English speakers and their wide variety of accents and dialects. It would be the 17th century all over again, when there was no standardized way of spelling words and so people could and did write - and, most importantly, print! - however they damn well pleased. It was a nightmare even back then, even though most English speakers lived in, uh, England. Thankfully Samuel Johnson came along and gave us standard English which, despite all its flaws, is an enormous convenience. The orthography is off, but it's off for everyone and so it's actually quite fair.
If you're still not convinced, consider this. There was a fellow from southeastern Asia giving a lecture in our university a few years ago, and it took my teacher about twenty minutes to decipher his accent and finally understand what he was on about at any given moment. The southeast Asian listeners, on the other hand, had no trouble at all listening to him, but they were quite baffled by the
rallienglanti accent most Finnish speakers exhibited to some degree. If everyone wrote phonetically, these people would probably have been unable to understand each other, and you could argue their texts had been written in related but distinctly different languages.
Also, /ŋ/ is NOT the only exception to Finnish pronunciation. Consider the word "hernekeitto" (pea soup for you non-Finnish speakers out there). Do you pronounce it with a short or long /k/? From what I've witnessed, the long /k/ version is more common, so why isn't it spelled "hernekkeitto"? What about the sentence "Anna kahvia"? It's actually pronounced "annak kahvia". What about "Anna ajaa"? It can mean "Anna is driving" or "Let me drive" depending on whether there is a glottal stop (/ʔ/) between the words, yet it's not marked in any way. I could go on, but instead I'll draw your attention to the so-called "yleiskieli" which very few people speak on a regular basis but which we take for granted anyway. If you want to make an impression, you write in yleiskieli rather than whichever dialect you happen to speak with your friends, workmates and relatives. Why doesn't this strike you as odd?