There are two aspects to this. How much are you playing your main guys and how many players overall are getting some regular minutes. As several have said, our main guys are actually playing more this season than at this point last season. It is not a big difference, but certainly does not support the notion that they are being saved for the playoffs or whatever.
The other aspect is how many total players are getting in on a given night, 9, 10, 11.... I have not gone though to check the numbers but on most nights in competitive games, we are only playing 9 or 10, seems about the same as last season. The difference seems to be that one night Griffin plays but then doesn't play at all for a couple of games. Earlier on, Vonleh was playing but now he isn't as much. One or the other seems to play. So over the course of a week, 10 or 11 players get in (other than garbage time) but in each game, it is still only 9-10.
I don't see an issue or a correction here. We have 7 players over 20 min/game (should be 8 when RWill is back). Then we have Hauser, Pritchard, and Kornet (8-10) jockeying for 10-17 min per night. Griffin and Vonleh (11-12) play some times in the regular rotation, but usually not. Jackson, Davison, and Kabengele (13-15) are end of bench garbage time only. Last season really wasn't much different, 7 or 8 getting 20+ minutes.
Tatum
Brown
Smart
Horford
RWill
White (Schroder)
Grant
(Richardson)