Hi Vydarr,
You bring up some great points.

I agree with most of them, but a few things to consider:
Re: Party Diversity - At first I was thinking of this as well, but remember one key thing Yoshida-san said - that Guildleves are going to be
Solo-focused - there isn't going to be a need for Guildleve Parties the way we're used to, now.
So it's not going to be as much of an issue for Party Diversity for Guildleves, because they're going to be refocused to be more Solo activities.
In addition, people will get to a point where they don't need / want Guild Marks any more for their class. At that point, if they want to still do Leves with friends, they can go wherever suits them (but again it's more of a Solo activity now).
So for SP Parties (out in the open world), we can still have parties as they are and diversified just fine.
Re: the other changes and spreading the players out, I agree that right now, it's tough (with low populations), but at the same time, *something* needs to change. The game is stagnating, there are 2 entire Nations (LL, Gridania) that are ghost towns and abandoned, wasting away.
It'll be good to get some traffic and incentivize people to move about.
The status quo of everyone on the server sitting, crowded in Ul'dah all day and going to Broken Water only is making for a stagnant, boring and dying gameplay experience (even with its many conveniences).