4) The thunderclap damage. This is where the perception differentiates from the paper. On paper the damage all adds up, perception the fact that a dragon is using an entire "action" and dealing 5 damage.... to characters capable of 7-9th level spells.... its like "why bother". All it does is trigger death saving throws (and the strip resistance of course), which is a solid purpose, but its feels out of flavor with a mighty and powerful dragon. This is different of course from the static charge or ignite abilities...because those are more "automatic", they just happen during the battle, and so can add up, as compared to a dragon's "action".
But here's an easy way to clean it up without changing the numbers....make the damage automatic. Alright you all are hit....take 5 damage, and now make a saving throw. Players are very funny about automatic damage, it immediately scares them, even if its low. I still remember the time I used a monster (reskinned from just a simple magic missile wielding mage). Even though I was doing about the damage a party would take even if they passed a fireball saving throw...they freaked out, because the damage was "unstoppable".
So by making the damage automatic it adds a little bit of terror in, even though realistically the damage is nothing at those levels. It also makes the ability easier for the dm. If the party doesn't have lightning resistance (either because they didn't have it or its already been stripped), the DM can just give out damage without doing a whole round of saves, speeds things up a bit.