I think one reason I'm able to enjoy some of these stories even when they're structurally weak is because I used to watch the show in the company of a friend and her young person. Of course, that young person is now a teenager and even the friend and I no longer have schedules that easily sync up. But to some degree, I think that effect did stick with me.
That said, I remember reading interviews with William Hartnell and Patrick Troughton, in whose era the show was probably most overtly aimed at children rather than families, and how they'd get mad if they thought a script was poor, or was condescending. They felt that having children as a target only increased the requirement for quality--or at least, as much quality as you can manage on the budget they had and under the time pressure they were under. (For the first six years of the original series, a season was 39-45 30-minute episodes long, and it took at least a week to make one episode, so for most of the year they were in constant motion.)
Series television is never going to be perfect. As leisurely as the modern Doctor Who production timetable seems by comparison with the original one, the truth is that every single person involved with the show is doing something else when they're not working on it, including Moffat. What concerns me is that some of the writing issues the show has are endemic -- they crop up episode after episode. Which means they're either deliberate, or they're blind spots, but not that they're the result of haste.
As to the Doctor being mean? He's always had a mean streak. Matt Smith was a actually kind of a bastard--he was just a young-looking bastard. But Capaldi is actually deliberately choosing, as a fan and an actor--to channel some of that early Hartnell irascibility (which, by the way, Matt Smith did as well, on occasion, usually when backed into a corner), and some of Troughton's manipulative nature.
The real difference is that Tennant and Smith both tried to be the Charming Bad Boys, so you forgave some of that irascibility because of their charm; and Capaldi deliberately isn't. It remains to be seen how that's going to play, long-term.
