What else can go bot lane instead of a Marksman?

As an aside, I'm going to refrain from talking about Mordekaiser in terms of balance or whatnot. I've literally been unable to play since just before the Juggernaut patch due to a certain amount of water damage afflicting a certain computer that may or may not have been the only thing that could play League in my house at the moment. I really do however want a relatively intellectual conversation about what sort of possibilities there could be to replace the Marksmen.

Okay so quick run through as to why the bot lane ADC class exist. For a start, we have 3 lanes and more specifically 3 lanes of enemy minions to farm and obtain gold from: Three people must exist on a team our top, mid, and bot laner. A fourth resource, the Jungle, along with all the added benefits there is to have Smite on your team and all the negatives (at least until S5) there tends to be with Smite in lane, causes a Jungler to be an exceedingly favored role on the team. As there are 5 players per team, the fifth guy is forced into a role without gold, the support. Because of reasons too long to explain, we throw that 5th member bot, and this causes a problem for the primary bot laner.

This is actually the funny thing about what we now know as ADCs in the bot lane; their entire existence is actually largely defined by their support. If Summoner's Rift was a 4 or 6 player game, I promise you you'd see much more interesting metas if they had enough time to establish. Tangent aside, putting two people in a lane together actually causes a gigantic problem; experience. Put two people too close to each other anywhere outside of the Jungle and exp points are divided among them. This means that two parts of the damage triangle, Burst and Tankiness, have much less value in the bot lane (Burst has a tendency to rely on its base stats, Tankiness tends to rely on the defensive modifications of their abilities, and both rely on the added utility they get from leveling skills). On the other hand, DPS scales incredibly badly in this game at least based on levels alone since the most prominent form of DPS, auto attacking, only gains the most mediocre power ups through leveling up. Thus, Marksmen by design are the most favored to exist in bot lane with their supports through how League inbuilt.

You know in retrospect this isn't at all a "quick" run through at all but oh well, now we all know why ADCs exist. I do want to say that by this explanation alone, Marksmen aren't the only champions that can go bot, as melee auto attackers probably would fit the bill as well. In fact, I'd argue the only reason why we don't see more mADCs bot is simply because of a lack of tools and popular stigma. Our most recent mADC for example, , was largely designed around facing a ranged threat. Even if the large majority of it was joking or casual, we all know of at least one Yasuo who rocked the bot lane if we've played since that long ago. Imagine if nearly all of Riot's advertisement and spoilers for him was centered around introducing him as a melee bot laner. Imagine if other mADCs would be rebalanced around fighting a ranged threat or if new ones are designed around it, that alone could introduce a whole new class to the bot lane other than simply just ranged Marksmen.

Mordekaiser is working around the exp problem by literally receiving 100% of the experience rather than getting the divided bit he gets from the support standing too close to him. That's cool and all, but it's not the most interesting way to solve a problem. I've pointed out that if mADCs simply had the tools to handle themselves even in a ranged environment, that it could actually help integrate them into the bot lane, but perhaps there are other ideas that exist that others have thought of. With that, I leave a question for those of you still reading: What else do you think can be done to help invite more diversity in our current bot lane meta?

EDIT: I think I've made it unfortunately unclear that I've been talking about this from a meta standpoint, and not just a casual standpoint.