it's not so much a trend...different REs do things differently. Some donors, no matter how high you stim, only produce a certain limit of eggs. It depends on how big the ovaries are, etc. A donor who typically produces 12 to 15 eggs will probably always get something close to that number regardless of amount of stims. To a large extent it's out of the hands of an RE as to how many eggs a donor produces.
Having said that, some REs do believe lower stims produce better quality, others simply do not want to risk hyper stimming a donor they are not familiar with (as is often the case) by aggressively giving high doses of stims. There may be some out there who have other reasons to stim lower but I cannot imagine they don't want their stats to be good so that seems illogical.
If you want a higher number of eggs (and I can certainly understand that -- it does give you a sense of confidence) best thing to do is find a donor who consistently produces 20 or 30 plus eggs per cycle (always check their egg to blast ratio if that's available), and cycle them somewhere where they have cycled before so the RE is sure of what he or she can give them to produce an optimal cycle. Typically using a clinic donor would acheive this.