I'd be concerned about RQ becoming easier to land.
Making the spell ground targeted doesn't necessarily make it easier to land, it just means it has greater potential. The point of this change would be to make RQ more reliable at closer ranges, and less so at max ranges (its currently the opposite). It would actually allow for more counter play since it could be easily be baited out to a max range cast, while you turn back and dive on her.
AP karma will easily knock out over half a squishies health bar with just the first part of it.
I usually suggest moving some of RQs initial damage to the explosion, giving the spell even more counter play than it has now.
You'd also be able to position it to almost guarantee landing the second explosion (or at least force an enemy to walk towards you, which is also very strong).
Adding depth without removing counter play. A ground targeted RQ increases Karma's options and out play potential, but it doesn't make it guaranteed by a long shot. Especially at max range, it will be easier to deal with at longer ranges. Besides, with this change you would be a lot more likely to see Karma players RQ for wave management in lane rather than gambling it away for just poke.
If Riot really wanted to make her viable mid, they could just jack up the Q damage against minions. It wouldn't really be elegant, but I think it would solve a lot of her problems.
It wouldn't solve any of her problems at all. This would make sense if damage was her issue for mid, its not. Her issue in mid lane is access, her spells don't allow her to manage waves efficiently and she also falls off as a mage since she loses access to the backline. This ends up with her having to rely on large AoE shields in the late game because there is little she can do beyond that - meaning she becomes less interactive as the game progresses. That's poor design.
And, despite all the hate her rework continues to get on the boards, I find her pretty fun. Her kit is straightforward and satisfying
Yeah I enjoy Karma too, she's my favourite champ. However, every bit of hate her rework has received over the years has been 100% justified. Riot threw the baby out with the bath water when they reworked her, they deleted basically everything about her and gave us something generic and incomplete. She was a rushed rework, and now she's just a poor design.