Yeah. And I mean, how often do you kill an enemy more than 15 times in a single playthrough? I played dark souls for like 250 hours and that happened exactly twice: when I needed to get a Channeler's trident for one of the achievements (which I got twice). In general I kill enemies nowhere near that. Maybe 5 times max per playthrough. Even when I farm chunks at the Kiln of the First Flame I don't do it that many times.
Well, when farming it's quite easily possible to kill enemies more than 15 times, especially if farming earlier on (Balder Knights for their sword or shield, rats for humanity, slimes for shards, Darkwraiths for chunks and slabs, etc). It's going to mostly depend on which enemies are affected by the respawn limit.
We have examples in Dark Souls of enemies which never respawned at all once killed (Boars, early Channelers, pre-Kiln Black Knights), and it seems like they're taking that concept much further this time around because they want all players - both farmers and those struggling with an area - to keep pressing forward.
And I wouldn't doubt there are probably many players who continuously die in the same area. With the knowledge that the game will eventually offer slack by removing enemies, those players may be more likely to stick with it, or it may attract players who didn't previously want to give the series a shot.
I don't mind this development. On some Souls playthroughs I farmed, on others I didn't. In the case of limiting farming it strikes me that this (along with other changes like stat-dependent armor) will make the game more of a skill-based one, where you can't so easily gather monster equipment, souls, and consumables earlier in the game to rip through everything with. And it should help out early PvP as well.
And as far as helping struggling players along, it could prove quite effective, though it's a double-edged sword. You may have a safer path to the next boss or section but you've also depleted the resources in that area. I think where it gets tricky is with those players who die a lot in the same area but don't particularly have a problem with that, and want to persevere instead of being given a break. In those cases this may be a non-ideal solution.