In general I feel that airside accessibility between terminals in an airport is a net positive. Certainly access to a wider variety of services for longer layovers, etc. would benefit everyone. Not everyone has precheck. Even as someone who has Precheck, it's a lot more predictable to walk airside than to have to go out and re-clear. Also, it isn't that uncommon for extra-alliance connections to occur, or even intra-alliance but between terminals requiring security re-clearance. I've certainly seen upset passengers who were in the process of missing their connections because of having to reclear security at SFO and other airports.

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2 notes (on Centurion Lounge to T2 visits):

1) October - approx. 630a, the T2 precheck was the longest I've experienced. It was probably 10 minutes total, but when you expect 5 or less ...
2) Christmas day early evening - precheck closed. Apparently a bunch of folks decided to just call in and not work. The nice TSA contract agent got one of the screeners to escort every few precheck people to the WTMD but we still had laptops out, etc. (Shoes stayed on). Expected 5 minutes total, ended up over 10 minutes.