These teams play on artificial grass because of the heat. It's to hot to maintain nice grass there (same with Rangers). Arizona's field was turning brown. Not an issue here in Toronto. MLB players still prefer natural grass.
I understand the heat issue just fine of course, but what I'm saying is that there's no real reason to undergo the massive expense of switching to grass and dealing with the drainage and water-wasting issues when the reason in favour of grass is really based on feelings and nostalgia while modern turf is easier to maintain and less wasteful. I pointed to those stadiums as examples of making it work, because clearly it can. The kind of grasses used for sports fields are non-native and require vast quantities of water. If they were able to use a strain of native or adapted grass that required less maintenance I'd be all for it. It's not an easy fix.