Pardon my ignorance, but are there any rumors that our navy want to buy this kind of ship that I don't know of? Because, as far as I can recall, I haven't heard anything about it at all. With that said, if there's a rumor about buying one, I do agree with your points. We don't need to spend billions of dollars just to buy a ship that will likely becomes a huge financial burden to operate and maintain.
This makes me wonder though: If TNI-AL really needs a dedicated helicopter carrier, why can't they just look at what PT PAL can offer? Granted, PT PAL's concept is not as luxurious compared to American's LHA, but it is still within our capability to build and to expand it in the future - not to mention that with that amount of money we probably can build several of this:
Source.
We already have several LPDs though. 1 dedicated hospital ship, 1 LPD converted to hospital ship and 4 'pure' LPDs.