I like what j rake has been saying regarding tempo vs efficiency. Also agree with MIR said about teams who push tempo having trouble guarding, and the evidence shows that is the case. When more teams played at a higher tempo, there were more offenses with a higher efficiency.
What would be great is is we (actually, they) could find a sweet spot where teams of all varieties style and tempo would have an opportunity to flourish. Perhaps those opportunities are there now, but it's just en vogue for coaches to slow things down and micromanage the games more than previously.
Ideally, I guess I'd like more continuity, good efficiency, and while I'm a fan of a higher pace, having a variety of styles able to find success would be ideal.
As _Fan's graph showed points per possession hasn't fluctuated much in the last 12 years, but style of play definitely has gone through major changes.
That's why I'm not sold on lowering the shot-clock. It would likely render certain play-styles obsolete.
I find a more uptempo, transition-based game more fun to watch. Especially when guys are trying to force turnovers and crashing Orebs, but that's obviously because my favorite teams employed that style. FWIW, 2009-10 K-State was No. 47 in the country at 70.3 possessions per game. They'd be No. 10 this season behind only Arkansas (70.7), LSU (70.6), and Iowa State (70.6) among power 5 schools.