It's relatively easy to see why Disney would see the RoA as a candidate for removal:

Can be replaced with a more recognizable IP that pushes merch(Cars)

While Disney shows the very sanitized version, parts of the source material is ... questionable

Less people required to run/repair the ships and rafts

As stated, until they announced it was closing, neither attraction was really pulling lines, nor had LL or G+
Do we think it's a stupid idea? Yes. Are we Disney? No. The last few big removals should have taught us everything is on borrowed time basically to Bob and co.