Well the title and the content aren't exactly...
Anyway to answer the Dragon stuff, I'd like to stress a couple of things.
First of all, if anyone's payed attention to the Jungle role for more than two seconds, it's really easy to recognize that some champs are way better at soloing Dragon than others. If you want to start preaching about Diversity in the Jungle, you need to know what that actually means. In this case, some Junglers are better at Neutral Objective control than others. You can name Udyr off the top of your head, and if I showed you a slideshow of all the meta Junglers, you can probably identify which ones can clear the dragon solo before the 8 minute mark (3rd clear, for those wondering why I chose that time). Trying to inhibit who can solo Dragons only hurts the meaningful distinctions in "Diversity", not help it. Unless you're one of those who thinks Diversity is making sure every champion performs exactly the same no matter what so that every champion can be picked for every situation.
Anyway the point of identification leads into the next point, why not just ward the Dragon at the 5 minute mark onwards? Unless you're top lane (in which case, Herald). It should be that obvious which Junglers
you need to constantly keep an eye on or at least keep a ward on the Neutral objectives. Dragon soloing shouldn't even be a problem unless you have extremely low pressure from your Mid, Jungler, AND Bot Laners, you're prioritizing your vision for something else (in which case, you're now having to deal with strategic diversity), or your whole team is bad (in which case, you have bigger problems to worry about)
But perhaps the silliest part of this thread is your recommendation to raise Dragon tankiness. That will do nothing. The best Dragon soloers do so because they have the sustain to chew away at the Dragon that early in the game, and sustain will always beat Flat defenses. Unless you bolster their solo defense to absolutely ludicrous levels, you're actually gonna make the problem worse since a lot of non meta Junglers can just barely solo dragon early and forcing them to chew away at it for even longer will kill one of their strategic options.