The problem with this logic is that most of his mid-range efficiency is based on his defender not knowing if he goes inside or steps back for the jumper, therefore allowing him to create separation.
I'm not totally against him shooting 3s but if he said he would definitely take the ball inside more I'd be more pleased. I do however already see improvement in his passing and defense which is very encouraging.
I think we're in agreement here, but if the argument for him shooting a lot of long-range twos is that "he pulls his defender from the basket", it should be even better if he's pulling him out to 24 feet instead of 18. Additionally, while he's not Rafer Alston with the ball, he's shown that his handles are more than decent enough to get by most PFs/Cs to the paint/rim. I don't see any downside.
As for the numbers, if he shoots 28% from 3 he gets as many points per shot as his 42% career mark from outside 10'. I have very little doubt that he can hit well above that. He shot 684 shots outside 16' last year (at an eFG% of 42%), or right at 10 shots per game played and 4.2 points per 10 jumpers. Love had 695 shots outside 16', but had an eFG% of 49.6% on them because he shot 505 3's last year at a 37% clip, or ~7 per game.
There are plenty of second- and third-order arguments to be made (farther from o-rebounding, closer to getting back on D on a miss, etc) that we could get into, but I don't really see a downside to him taking a step back 5 times a game or so...or even running some high-P&Rs or ruboffs after the switch where he's taking a 3 over Dame's man, or Dame's blowing by a big with less help able to rotate down. On a team with 3-4 really decent 3pt shooters on the floor at one time, that's pretty decent.
For you coaching guys out there, is there enough spacing to run a side P&R where the screening big stays outside? You probably can't have a shooter posted in the same-side corner (so you'd need to swing 2-3 times to get a corner 3), but I seem to remember Love doing this all the time and even guys like Ryan Anderson and Steve Novak pulling it off.