Sure, up to this point, the show has been a lot more sanitized and formulaic. But I have a theory about TV, which is that the first few episodes of any show are about selling it to the network suits, putting them at ease about the money they're investing in the show, and that means giving them something that looks familiar and formulaic and conservative to appease their expectations. So it isn't until after the first half-dozen episodes or so that the producers are finally able to start making the show they wanted to make all along, to gradually strip away the protective camouflage of exec-friendly procedural formula and begin to get more daring and innovative.
I think the oppsite is true, a show will normally put the wilder stuff out there first, then after feedback from the studio, the nework heads and the audience shows are toned done and altered. We've never had gotten the Daleks if shows followed your theory, they were a huge risk for Verity Lambert at the time.
Different shows are run differently. And in general they're run *very* differently now than they were in 1963.

Some shows get a ton of notes in the first season and then left alone from then one so long as the numbers stay within profitability margins. Some get their showrunner pushed out over politics and some are given free reign to do whatever the hell they want.
I think it mostly really depends on the individual studio's culture and if there's anyone at the executive level that has an agenda, for good or ill.
As far as Constantine goes...I'm just about hanging in there. I generally have a "3 strikes & you're out" policy. As in "3 episodes I wish I hadn't watched". So far it's not doing much that's very interesting, but at the same time it's not actively offending my intelligence. Still, if it doesn't improve soonish, I can't see myself sticking around.
It probably helps that I've never gotten around to reading 'Hellblazer', nor do I recall seeing the lead actor in anything else.