I fly in the US, in a hub and spoke system. I gave up along time ago worrying about "block times". off and in times. For me it all comes down to safety. There is a big push for on schedule/early departures for reasons you stated, but now fuel consideration are getting thrown into the mix. Large planes tend to burn more than small, and tend to be harder to move around if heavy. 1 minute saved for a larger plane, may be twice the fuel savings, if that is the driving factor.
If I am cleared to push back, and the ramp or ground control wants me to hold my position, I comply without complaint. There is usually something going on I can't see. The Captain that was "going to report", for being slightly delayed to expidite the flow, either had 1) A long day, 2) Doesn't get paid by the minute, 3) Or has a personality trait. that makes one say under their breath , "What an a$$hole".
There are going to be numerous programs out there, trying to tweak whatever is on the agenda at the time. Saftey should always be paramount. Start with that and see if you can fit the other in when needed. Never let, "Keep it safe", interfer with whatever is going on.