[steven]

If you're planning on coming to Japan, knowing how to read romaji is definitely important. City names, intersection names, and some rail stuff are sometimes just written in kanji and romaji (no hiragana or katakana). I think Japanese people will agree at least with this-- if you are in a place you are not really familiar with, that romaji will help you read the kanji. This is because there are multiple ways to read kanji... you'll know it's gonna be one or the other (and occasionally one more or so), but the romaji makes it final. At least that's what I've been told by some Japanese folks.

Other than that though, like everyone else is saying it's not something you wanna go out of your way to study.

" You'll understand how they construct pronunciation better, and work together to make a word."
I hate to disagree, but I'm not so sure that just studying hiragana alone is going to help with pronunciation. I've seen plenty of people who study hiragana and katakana and have absolutely terrible pronunciation. I think it would help to study writing/reading hiragana in conjunction with the sounds they make. Even still though, you don't quite get the whole picture as there are many cases when things aren't pronounced exactly how hiragana says they should be. Also, hiragana doesn't express intonation. While a Japanese who is just learning to read hiragana reading a word (in context) can probably say the right intonation, a person learning Japanese as a second language would struggle because it's not a language they've been exposed to for 4 years or so of their life.

A good example would be がっこう vs ちゅうがっこう. You don't wanna say the が in ちゅうがっこう as you'd say it in がっこう. You wanna soften it up-- a pronunciation dictionary I've seen (and I've only seen a one) writes it as a か with a maru instead of a ten-ten. Another example is おはようございます. As English speakers, we are all tempted to apply some of our pronunciation rules to that word, thus making ご or ざ (or both) strong "syllables" (technically moras in this case or something like that). I think the correct way to pronounce that is to have the pitch of the お be lower than the rest, and that's pretty much it. However, most people don't say it that clearly- they'll just say something like あざーす (or any of the variations that exist). At any rate, I don't think looking at it too technically like this at the start is gonna do much good. I do think, however, that listening to correctly pronounced Japanese while studying hiragana/katakana will help a lot (and the learner will probably pick up on some of the details I just covered naturally).

But yea, if you listen while studying Japanese words in hiragana, you will be way ahead of the person who is dealing with romaji. I also think that romaji, being written with the alphabet, makes it that much more tempting to really mispronounce words (or pronounce them as an English speaker would be inclined to do).

As far as "correct" romaji goes, I think hepburn is the closest to that. There are some styles where you could write し as "si", but that doesn't really get an English speaker anywhere close to correct pronunciation.