I'd say there's a good reason for forcing players to play as humans, if only because human cultures in fantasy worlds are the ones that are the less extreme ones, meaning a player's choices will more likely match the background of the character in question without railroading them. To show a good example of this, the Dalish Elf origin in first game should be a radically different path than that of a human noble or a dwarf commoner, yet some players will choose to be a radically different Dalish by being more accepting than someone who grew up being taught that their race was completely different than the others and that accepting human culture was to lose one's elven soul should turn out to be.
Interacting with the Qunari in the second game shows that they would be even more extreme than the Dalish, meaning that while players may want to play as them, their values would more than likely clash with most people's gut reactions.
While some races may be more understandable, you'll always run into a stumbling block somewhere along the road. Look at Mass Effect. Sure you know the Krogan are mostly fierce warriors who prefer to use bullets over brains, but when you hit moments like the idea of wiping out the genophage versus sacrificing honor, or the ideas they hold of other races, you'll likely think in a much different way. Or just look over at Legion as a good representation of why the geth would be so hard to understand.
Roleplaying games are all about working within the role of a specific character, and races serve to complicate the idea here when they are radically different than each other.
Do I fully support racelocking? No. But I can see valid reasons for it besides technical limitations.