To be completely honest, a dragon that only breathes and flies away to recharge its breath is pretty boring to me, and why, as a DM, I use the "dragon's cave" trope to try and limit this otherwise incredibly effective strategy.
Possibly, but I play monsters with tactics I think make sense for them. And, in addition, I wouldn't just fly away and wait for my breath weapon to attack. It would be more "fly away and then come back to attack the guy who's trying to hide in the back".
I sometimes set up multiple goals for the party when doing any encounter - but I'm even more likely to do so for a dragon fight. Maybe the PCs are just trying to escape, or they're trying to get the McGuffin to the the Circle of Importance, or some other goal. The dragon will vary their behavior as well depending on what's happening.
Completely agree on the lair actions though. There's great potential for fun in them.
So if this were a black dragon encounter, the lair actions would be used to divide and harass the party and in particular anyone with a concentration spell up. So pull the wizard away from everyone else with a surge of water and then attack them when they're prone. In that case the dragon would attack, tail slap the wizard and then when someone came to the rescue wing buffet and try to get away.
Whether that tactic works or not is a whole other issue. What would be boring to me would be to run a dragon (particularly an adult or older) as just a big bag of hit points with the occasional breath weapon. There are other monsters for that kind of encounter.