I'm not sure about RTD being a bad writer. I think Moffat and RTD excel in different areas. RTD was a much better character writer. His dialogue was always excellent, and when he focused on small set-pieces involving a few characters and large numbers of dialogue (eg, Midnight) the result was always excellent. On the other hand, he couldn't construct a coherent narrative for shit. Moffat can construct excellent narratives (within the constraints that Doctor Who's filming places on him), but he can't write decent dialogue or characters for shit, as shown by Amy in the A Good Man Goes to War.
I'm one of the great RTD defenders in this thread, really. RTD is an incredible character writer, and imo there hasn't been a single character since 2010 with the charm or sharpness of those he wrote.
The overall overarching point is the same, though. Like, RTD was better at keeping Doctor Who front and centre with the BBC as their #1 show, Moffat's era has slipped. He was better at not showing his hand to fans, or letting on when he was angry. All that. On the flip side, Moffat has been able to position the show much better abroad, so clearly he's not a complete disaster as show runner, the same way that for every 'Jesus Doctor' moment from RTD there's one like the scene posted above and such. In general, though, I'd argue RTD was a better character writer, while Moffat has been a better plot writer, yeah. RTD was undoubtedly better at running the show, though, but a great deal of that was also down to those he surrounded himself with - Collinson, Gardner, etc. Moffat has had musical chairs of everyone but him up top - though if you believe the rumour mill, a lot of that is down to him acting like a spoiled/entitled child, so... it's tough to sympathise.
On the subject of RTD, there's one scene I always think of as a not-so-obvious example of what a masterful writer he is. Anyone can point to Midnight (same way anyone can point to Blink for Moffat) or Parting of the Ways, but the truly brilliant thing I think of from him is in Utopia.
It's essentially a info dump scene; Jack goes into the radiation flooded chamber to fix things so the rocket can take off, the only man for the job because he can never die. He asks questions. The Doctor leers on the other side of the window, bathed in this red light, and in that instance looks and sounds cruel as he recounts running away from Jack, a friend. There's a real darkness to that scene, and the dialogue is just perfect. It establishes a new relationship for Jack with the new Doctor, checks the old one, and reminds/dumps a ton of information for the non-Torchwood-watching audience. On top of that you've got cut-aways to Martha, who is listening on the intercom and being gutted
again as it's revealed Rose was the one who saved Jack and gave him his blessing and curse. A chunk of that is down to Freema, too, but there's just... that moment is great. "What happened?" "Rose." Martha looks crushed, again. On top of all THAT, the discussion brings up terms like regeneration, which Yana/The Master is reacting to as he begins to remember.
It's a wonderfully dense scene, and I don't think there's been a scene quite as masterful as that since in terms of accomplishing so many things at once, really. It would've been so easy to hand-wave all that stuff with some fast-cutting, Doctor dancing around, hands through his hair, doing his fast talking act. But, no - in a really deft movement, he does the exact opposite and slows an episode that is otherwise breakneck to an absolute crawl. Just two men, talking, with another two people listening in.