Dashes should have more downside

I was just thinking about the problem a lot of champs have with being easily kiteable and started wondering why that is. An idea i came up with is dashes have basically no downside and often an upside (extra damage or other effects) and are super available as far as champ picks.

To me gameplay would be a lot more creative if there was downsides to using dashes. This could take many forms like perhaps very high Mana cost on some champs like ezreal e, or perhaps reduced damage for some time period like do 50% less for a second or two.

The fact dashes are so strong causes a ripple effect where older champs have to be reworked constantly with insane movement speed abilities to remain relevant. I'm fine with a nicely timed dash by an adc to avoid a nunu snowball, but feel he should be tired after since moving a champion should require a lot of resources and perhaps he should not instantly be at full dps.

I feel dashes should fall into certain categories where they either are all in dashes (only to champions), they have really high Mana cost, or they greatly reduced damage. There could be other categories but they should always have a significant downside. What do you guys think?