[2019] With the introduction of the new defensive instants in Legion, expanding the skillbar is way overdue

Nothing punctuated the limitations of 7-slot skillbar more than playing summoner before. You likely had multiple auras, curses, minion skills, movement skills, Convocation and an offering skill of your choice. Maybe two. Juggling all that was nearly impossible on just 7 slots, but that was counteracted heavily by the virtue of summoners being painful to play to begin with, thus unpopular.

Now however, look at the mandatory skillbar of the archetype GGG is pushing, sandy blood memlee. You have your attack skill of choice. You have an instant movement skill to dodge attacks. You have an instant defensive skill. You have the new blood/sand toggle to allow you to fully use your skills. You probably want to have an ancestral totem. You also will likely use at least one Vaal skill, totem or not. You might also want to use a golem for accuracy or regen. That's 6 skills already, all that you must have hotkeyed and ready to go. This does not include your non-toggle auras, potential curses, utility skills like Phase Run, Warcries (kinda important for a Berserker), Banners, potential single target attack skill of choice, or a potential map mobility movement skill, or one that allows you to clear ledges if you run Shield Charge.

Using all that is heavy on your gem sockets, and that is a larger balance consideration that ties in directly into game mechanics. I'm not asking to change that. But adding 3-5 extra slots on the skillbar comes at no cost to the core gameplay or balance at large. And frankly, would be one of the biggest QoL to come for many builds.