In my view, this is an indirect reason for many of the complaints about WotC adventures. The objective of allowing the PCs to gain one or two levels by the end of the adventure combined with the need (according to the rules) to fight X encounters in order to gain the necessary experience usually means that adventures are padded up with more fights and encounters than they actually need.
It makes me wonder whether objective experience rules are fine in a sandbox campaign (being an essential element of the trade-off between risk and reward), but unnecessary (or even detrimental) to a more scripted game.
What I find myself wondering is why WotC doesn't simply give XP for noncombat encounters.