Why would any sane person compare the inventory functions from a Gen 3 game to a Gen 5 game's obvious improvements? That is, quite simply, an unreasonable argument to make. GF improved on what was an already functional and well-deisgned system in Gen 2/3 and made it better in later Gens. That happens to multiple game mechanics in the Pokemon series, and it's what should happen all the time. All that's saying to me is that it's hard to go back to an earlier Gen, which is a sign that things are simply getting more and more refined like they should. :\
Also: I noticed nothing wrong with the FR/LG visual style, and various improvements like the magnanimous VS Seeker made it all the more worthwhile.
The reason for vast expanses of water being threatening, to me in particular, is that every tile of water is a chance to get a random encounter, which is something to mark the water sections against. But keeping a good supply of Repels should be wise in SP anyways, so as to make travel across a region and through routes more accommodating (sans HM moves, of course).