Mobile champions need downsides.

Champions with dashes or any sort of movement put into their kit need some sort of downside for being able to use them. Champions coming out are being given dashes and a lot of damage as well. , The mobility that champions have now made them safe while fighting and give them good escape opportunities as well.

Example is the aatrox jump. They had to nerf this because you were not going to be able to get away if he came in on you. Many champions now have the same ability to just dash to you and there is no escape. while albeit not as strong as aatrox

The most infuriating one, In my opinion, is riven. I think she is strong right now with conq and the spear of shojin and im fine with her having damage but the problem is her kit gives her movement and dashes that actually give her too much gap closing potential. She can move faster by q through animations into e to close more ground than characters could walking that distance. The fact at 45 cdr she gets a shield every sec. just adds imo

I really think riven takes some skill to play, getting good at the animation cancels and auto attacks but in reality, the champ is good because her kit has a stun, shield, three jumps, one that allows you to go over walls.
As well riven can outrun many champs by just using the q dashes. While I think this is fair the fact remains that if you catch up again she just q's away again. (unless your champ has cc)

Just an example of a champ with high mobility high damage.

There is no downside to having mobility only not having it.
I think that mobility abilities need longer cooldowns. I think there has to be a clear price with mobility even if its lower damage or just not being to use that same ability to get out. leblanc w (takes no skill to double hit w) yas e (takes some skill to e right direction) Riven q,e(takes skill to animation cancel for autos but no skill to hit q)

Zoe's r one of the most balanced movement abilities, Clear upsides is the extra range on q, closing distance for e's but the down side is you go back to the spot you cast it from. So players can punish that, but some of the dashes do not have such counterplay or such big downfalls. Tryndamere s spin dash is more balanced than riven q's as trynda can't just dash away again immediately.

To me, there is no thought that goes into playing mobility based champions with dashes. As their kits are overloaded goody bags. Yasuo, Riven, Kayn, Irelia, dashes haven given champs over tooled kits that make them better in almost any situation in comparison to champs that don't have dashes.