The simple reason I haven't switched email providers: all my online accounts, as well as many offline ones, are tied to my gmail account. Yes, I can set up forwarding, but that defeats the purpose of switching providers IMO (for me, the purpose would be to move away from Google completely ). I don't want Google to read any of my emails period, so forwarding is not a sufficient solution.
If you do change, get a forwarding service or your own domain so that the same mistake doesn't happen again.