It's cool you want a very diverse botlane - an exchange is needed

Then I want more marksmen top, mid, and jungle.

Yet people weren't very welcome to the idea of Vayne top, Lucian mid, etc.

Marksmen don't have the survivability like other toplaners/midlaners but now that you want to introduce multiple classes into botlane, marksmen are getting a kick in the balls since over half the roster relies on crit and can't scale or do their job efficiently anymore due to game length and itemization.

I have no problem with a botlane introducing more carries but I do have a problem where some of my favorite champions aren't viable in other roles. People argue there are many champions in mid/jungle/top that with only about 2-4 ADCs have ever been able to be in and are hardly picked there. The same argument can be used with botlane and the scarcity of Ziggs, Cass, Ryze, Morde, Darius, etc.

Give marksmen the stats to survive in other lanes as well because now the game is shifting to a point where an entire class is almost irrelevant.

The notion marksmen are only going to be DECENT botlane isn't going to cut it. That's basically saying there will be non-marksmen meta picks. It's like saying you only want bruisers/tanks to be DECENT toplane and have other classes fill in but yet Riot was quick to come in and make toplane pretty much melee reliant due to their survivability and conqueror.

Marksmen don't even have the burst/damage to keep up with enemies late game anymore which was why they were a threat. Pre-8.11 they hit that power too soon, but now they hardly get close to a good DPS amount, get the items needed, or deal out the same damage.

Couldn't IE just have a change where a % based of your critical strike chance is changed to bonus critical damage? This makes the 2-item spike weaker but the 3-item spike just as strong to make ADCs relevant.

The game is all around bursting squishies, damage is nuts across the board, and marksmen have lost a lot of their value in the game.