1) Because rewards programs can be so lucrative per-category, I wind up using like 5 different credit cards constantly. That's too thick to keep in my wallet, so I never bothered before... but now it's effortless on my phone. Now I basically get 3-5% back on most stuff instead of the old 1-2%. It adds up.
2) Chips seem to degrade after a while, as anything contact-based seems finicky. Apple Pay doesn't always work on the first try... but it always works by the second. Which is more than I can say for credit cards, god only knows why.
So now I really just keep one physical credit card on hand -- the one that gives me most rewards dining out, since you need a card to hand them (in the US anyways) -- and to use for the occasional instance a store's terminal doesn't accept Apple Pay (mostly public transit vending machines these days).