Surely the whole point of indoor nets are to get a few overs of bat-on-ball and getting your arm over? Not to be in full swing ready for your first game.
For most people, it is the first time their kit has come out in 5 months or so.
The fielding, etc can come later.
Indoor cricket is a fairly new invention and very difficult to organise for an individual club. Then if you join a league, you can only get 6-8 players a game each week. Not really beneficial for those without a game.
Outdoor nets and pre-season matches are for focused practice.
Unfortunately clubs take the league they are in sort of serious and with the lack of people genuinely interested in indoor (very small % of the cricket community and from the league I know it's the lesser end of the talent pool that play more too (not that that matters))
So few clubs are willing to rotate players in their teams as that might mean losing.. Heaven forbid losing!
Pre seasons seem to becoming almost competitive games rather than regarded as purely another training tool