What is the advantage of maxing out a TH?

Hey guys, I guess its to late for me now since I am currently upgrading my TH to #10 but I've been hearing a lot about maxing out bases before going up in town halls. I was wondering how advantageous that is. I'm level 82 and some people say that I'm screwed when I don't think so at all. I've been playing for about a year now, have spent $0 and have been maintaining a strong clan. I usually get everything close to maxing out I suppose but I've never done it intentionally. Rather I've always upgraded my TH when I was getting close to maxing out. My thought process is that quantity defensive buildings > level of defensive buildings ***** within reason! Let me throw out an example, lvl9 archer towers do 56 damage while level 10 archer towers do 64 damage. Rather than worrying about maxing out the archer towers to lvl10, I would build the new archer tower that I unlocked and upgrade that to a decent level. By having this new archer tower, your bringing in a whole new set of '56' damage (or whatever level its upgraded to). That level of damage will 99% be greater then the added '9' damage from the maxing out. I guessing here so bare with me but I would bet that for the same amount of gold that it would take to upgrade the tower to lvl10, you could build up a new tower to a decent level which would be more beneficial? Someone else must have thought of this before, so please someone enlighten me about the downfalls of premature th upgrades.
* I have heard about the loot bonus but is that honestly all that much? I usually still raid for about 100k-200k each time in the gold div 1 league

I'm not going to touch much on the archer tower question you put but it's not Loot bonus, but Loot PENALTY that you should be watching out for. Every Town Hall level you go up, you get penalty for attacking a lower level base. For example if you are Town Hall 9 right now, attacking a Town Hall 8, you'll get a penalty of 10% less loot. But once you are Two Town Hall levels above a TH level (so TH 10 attacking TH8) you lose 50% of that loot. The 200k that would have turned 180k is now a whooping 100k. So consider that before you upgrade.