I would generally say no, it's not bad.† But it's probably more considerate if you build your armies in moderation somewhat, otherwise some might tag you with the ol' "hoarder" moniker, and a lot of people consider that almost as bad as a scalper.† I personally don't, but I've seen many a fight over at RS over this issue...
I only army build with OT figures for the most part, but generally limit things to about 7-12 of any given army builder.† With the prequel figures, I may pick up a few extras here and there, but nothing more than 3 or 4 altogether.
My general practice would be to probably nab about 4 figures at onset, like when they're first released.† When they're brand new and red hot, I'll try to leave what I can behind, or maybe grab some of them for friends.† But I'll personally only take up to 4 at one store store for the first few weeks.† But if I see a bunch of them on the pegs at once, to the point where I can take a nice hanful but still leave many behind, then that's definitely fine.
But once a figure's been out for a good 4-8 weeks, especially if it's actually starting to pegwarm a little, then hell, clean 'em all out if you'd like.
I guess it's times like say, Midnight Madness, where one guy may grab all 10 Royal Guards and every single Clone Commander right in front of a bunch of other collectors who get nothing, that it really becomes a messed up problem.† At a figure release like that, I just grab my required 2, and wait 'til later to get some more if needbe.
The Target Clone I guess would be the prime example right now on potential "evil hoarding", since it's so HTF and many people have none, while others escaped from Target stores with entire cases.† Something like that I think is pretty messed up, personally.
Just try and keep an eye out to help your fellow local collectors or forum members with army builders if they may have missed out on them entirely.† Otherwise, knock yourself out, amass your armies, and enjoy...