We already do, and it's called Fresh. "What's hot" is arguably a part of the front page on Tapas (Trending being the equivalent). However, it's not as useful for multiple reasons:
1) the genre tabs aren't as conspicuous.
2) the fresh page itself isn't conspicuous.
3) I imagine that on average, Tapas has more comic updates daily than Webtoons. Why? Because Webtoon readers prefer longer updates, so the same creator with the same comic may update every week on Tapas, while they combine two updates into one and post every other week on Webtoons (which is what I'm doing). This means comics disappear off the Fresh page very quickly -- they get pushed off the first page by the constant stream of even newer updates.
I don't think Tapas can do anything about 3), but 1) can probably be addressed.