I think there are several ways to play with the flavor profile. I'd pick the method that best fits my overall goal. For example, if I would like more esters but also planned on harvesting and repitching, then I would adjust my pitching rate and fermentation temp to increase esters but still oxygenate so I end up with relatively healthy yeast. If I didn't plan to repitch I might oxygenate less or skip it and aerate instead. If I wanted reduced attenuation I agree with Jonathan and would up my mash temp, change grist, or go with a less attenuative yeast.
Bingo. First off, I wouldn't necessarily think of it as "purposefully stressing yeast" - to me that sounds like you are going so far to the extreme that the yeast is going to do all kinds of horrible things. But there are certainly several ways to adjust the initial conditions of the wort/yeast to get the results you're looking for. I wouldn't necessarily go out of my way to stress the yeast, but using lower pitching/nutrient/oxygenation rates are certainly all valid options available to the homebrewer. I do I think I'd choose to manipulate other factors first (mash temp & fermentation temp primarily).
I think homebrewing has come along so far because of the quality of the yeast that has become available, and because most good homebrewers place good fermentation practice as their top priority (and rightfully so). But I think that this has also led to some brewers falling under the impression that you absolutely have to
pitch as much yeast as Mr Malty tells you to in all cases. I don't see that as the case. I think if you are managing all your other factors properly (aeration and temp control), then you can pitch at a lower rate in some styles and have excellent results. I'm not saying that 1 vial of yeast could work for 10 gallons of barleywine, but I like to pitch about 1/2-2/3 of what Mr Malty recommends when I'm brewing a hefe to get the flavor profile I'm looking for.