A new algorithm may be incompatible for ASICs. It isn't easy for developers to just make a fork and make all the users and miners to switch to a new client. It doesn't benefit those with big ASIC farms since all their hardware would be wasted.
And that is really bad? If the new algorithm is incompatible with asics, maybe many of the users (who are far from mining because of the dificulty and costs) will start to mine themselves for the stability and safety of the network...