I can appreciate the "good in a cheesy-bad sort of way, and hey, it was the 90s" argument.
But I am unconvinced, even (especially?) when benchmarking it against Roland Emmerich films.
The chief problem with this movie - other than the controversy surrounding the cost and sinking setpiece - is that it came after Costner was enjoying immense success from his beautifully-directed Dances With Wolves, and his star turn in Prince of Thieves as the only Briton from the American Midwest. On the heels of that came more overly ambitious and way-too-long movies, beginning with Wyatt Earp and Waterworld (which admittedly, by comparison, only FEELS three hours long), culminating in The Postman, and finally petering out with Thirteen Days. His ambitions seem to be scaled back considerably in the new century.
All that said, I felt his best real drama is long behind him (The Untouchables), and other than that, all his good movies are sports movies (specifically his baseball movies, but I liked Tin Cup as well). Even as a leading man, he just works better when he has a chance to disappear into some good-ole everyman role, and not even the Tom Hanks, Jimmy Stewart capital-E Everyman role, where we're compelled to watch HIM perform, but when he's one of us, and the story is the main character and he is merely our avenue through which to experience it. In that way, he's like Nicolas Cage: very serviceable if he's an experiential character, and not someone who's being asked to carry the story on his own back.
But sad to say, this defense, admirable as it may be, does not persuade me to commute the sentence on this particular film.