Plugin effect and synth presets get a bad name among digital musicians, for two reasons:
But I love presets, because they make me far more productive. For the same reason, I'm a huge fan of general MIDI samplers--Cakewalk's TTS-1 general synth has been an unexpected perk of Sonar so far, and on Pro Tools (for lack of better options) I often found myself working with their X-Pand! offering. In fact, general MIDI synths combine the best of both worlds--they present a wide range of sounds, and limit the amount that you can typically spend tweaking them at all.
As a result, I'm able to cut through the urge to find that perfect tone, and instead I get on with the process of making music, which is where I think the creativity should actually be. Working with budget sample libraries does carry risks, but in general it simply means that I learn which sounds are limited and should only be used in certain circumstances, and which ones are simply bad and should be avoided, instead of trying to fix them up.
In fact, the more options I'm given, the fewer I tend to use. I've been looking at sample libraries lately, because I do love having orchestral sounds available, and those tend to be the most useful for work compositions. And invariably, what I'm looking for is something that will work right out of the box. Life's too short to spend all my time twiddling knobs instead of tracking music.