GPU mining has benefits to the network not discussed here, which is why coins like Monero are unlikely to go to ASIC. New blockchains like Ethereum can perform different types of calculations on the blockchain. Because of this, you are unlikely to ever see ASICs on Ethereum. There will always be a significant number of coins that are ASIC-resistant. The chances that one of those coins becomes profitable is higher than picking a singular coin and hoping that that one coin succeeds.
There is a situation where ASICs are beneficial. If you have a large equipment budget, access to very low cost electricity, and you are OK at sticking to one coin for the long run no matter what - ASICs are by far the best choice for you. However, if you want flexibility and freedom from a singular coin, GPUs are the way to go.