I agree, Dinoland is far from Disney's best work.
But it DOES somewhat make sense when looking at Animal Kingdom's history and business plan.
On opening day in 1998, AK was simply TOO ambitious of a project--- one that was too much of a departure from Disney's usual "formula" for theme parks. While it's good that Disney took the gamble to build something so unique and different (no one can deny that AK is WDW's most beautiful and heavily-themed park), it didn't quite work with guests as they had hoped.
Of course, it took Disney a year or two to realize that (understandably, they had to give their new park time to "grow" on guests).
Disney already had the Asia expansion underway, including an E-Ticket--- Kali River Rapids. Unfortunately, those alone weren't enough to turn the park around.
By 2000, it became clear AK needed something BIG. Whether Disney should have quickly dusted off it's old "Beastly Kingdom" plans (or should have had something else in the pipeline) was basically moot at this point. Anything they'd greenlight in 2000 would have taken YEARS to build. And AK needed a quick fix THEN.
That's how Dinorama fit in. It gave AK a new attraction to keep people occupied while Expedition Everest was being finalized and built. Without Dinorama, AK would not have had a new attraction for more than FIVE years.
Sure, we wish Dinorama could have been given a bigger budget and more planning, so it didn't look "cheap". But it WAS cheap--- and more important, QUICK. Something Disney could get up-and-running right away.
In hindsight, Disney should have had "AK Phase 2" on the drawing boards and ready to go BEFORE opening day. Maybe you can blame that on budget cuts. Or maybe it was simply that Disney was caught off-guard with AK's shortfalls. Or maybe it was that, until AK, all other Disney parks opened with rather minimal offerings, with the next big E-Ticket coming several years later.
Either way, Dinorama WAS and IS the band-aid that has kept AK from hemmoraging as they wait for Expedition Everest to make its mark.