I own 2 tanks, both bowfronts, but I like flat fronts better.
So why do I have all bowfronts then? The 36 gallon looks better in a bow from a 'furniture in the room' standpoint to to non-aquarium people (like my wife). Has some flair to the tank and a nicer looking stand than non-bowfronts in the same size range. This was ok with me as I get a wife approved tank in the living room where we spend all our time (and even she sees it as adding to the room, not somethign she just puts up with because I like it), and the 36 has a mild enough bow that the warped, magnifying glass look is minimized.
Same thing with the 3 gallon, it just happens to be the perfect size for my desk, was a great price, looks great with the seamless bent front corners, is good to look into as the bow is very slight.
Bottom line - I would prefer a big (and wide front-to-back) flat front tank from the fish & plant keeping/watching end of things, but a largish mildly bowed tank is more pleasing to the non-fish persons eye (flat=old & common, bow = new hotness & style for some reason) and as 'furniture'.
As for bows being hard to plant/scape - I don't think the bow causes that, only the width of the tank (tall, long, and narrow like a 55 can be hard to work with). Check out the 2 tanks in my sig (lots of pics) - I think they turned out nice and they are both low/mid light bowfronts.