Much is used more in negative than in affirmative contexts. A lot has no such restriction, and that's one reason why it's so common.
- I've never liked it a lot.
- I've never liked it much.
- I've always liked it a lot.
- *I've always liked it much.
Another reason a lot is common is because it doesn't distinguish mass from count nouns; there's a similar pattern for many, with plural count nouns.
- I never eat a lot of them at once.
- I never eat many of them at once.
- I always eat a lot of them at once.
- *I always eat many of them at once.
Much and many are on the NPI list, but they're not quite NPIs; there are a lot of affirmative environments where they can appear grammatically. Of course, as quantifiers, they already participate in a slew of idioms and odd constructions, so that's not really news.