If it gets easy to mine bitcoins on a PC,bitcoin will lose it's most valuable feature-it's scarcity.
What people use to mine won't actually matter because of difficulty adjustments.
ASICs mean a more centralized world of BTC where a few manufacturers and a few pools control all the income. What is so great about that? Satoshi designed it so anyone could mine and anyone could earn BTC.
I have never understood this reasoning. People with more resources will be able to do whatever they're doing right now no matter what miners are in use. Miners running ASIC farms would just run PC/GPU farms instead. You could also just as easily buy an ASIC miner like you would have a mining PC, so it's not like there's an insurmountable barrier to mining.
It's also worth noting that it would be theoretically cheaper to attack Bitcoin if non-specialized hardware were viable. ASICs turn into bricks after being used in a successful attack (assuming Bitcoin dies), whereas PCs/GPUs would retain their value. Either way, it's best to simply leave things alone, especially because there are no problems to address in the first place.