Cruz, like Reagan will appeal to the American people. Cruz’s policies are popular with the people. Those policies have made him unpopular with the establishment.
That he is unlikable is a myth. His favorables are at the top of the entire list of candidates, while Trump has the highest unfavorables of all.
He has rather impressively managed to repeat his unpopularity in the Senate with his unpopularity with his fellow candidates. Ben Carson, of all people, just hates the guy.
I'd be all-in on Cruz if the national political landscape mirrored that of Texas, but it doesn't. The country as whole is not nearly that conservative. We need a candidate who can actually persuade fence-sitters to embrace at least some conservative ideas, but Ted is much better at drawing the lines between "us" and "then" than at persuading people to cross over.