I'll try and avoid the politics and simply say this:
The political debate as such is a real killer of investment into any comprehensive solution. It leads to a situation where the only willingness to invest is into things which make a quick profit and/or have a certain role to play no matter what happens next.
This approach will not get us to 100% renewbles but it will get us to somewhere around, as a rough order of magnitude, 75%. Hence AGL, for example, spending $295 million on 12 x 17.5 MW internal combustion driven generators whilst having site permits to double that and at the same time buying the rights to develop a pumped hydro scheme as an alternative. They're hedging their bets so to speak but they're not aiming for 100% renewables in the medium term and nor is anyone else of significance.
Related to that lack of certainty and short term approach comes higher than necessary costs and realistically, we're not far away (3 years at the most, probably less) from facing the inevitable with industry demanding that government bridge the gap between internationally competitive energy prices and Australia's actual, far higher, prices which are the direct result of government stuffing things up over an extended period.
On the politics itself I will simply say that regardless of which side you are on, your side most certainly has contributed to the problem and pulled some elaborate stunts in all of this. That includes pretty much everyone really, I can't actually think of an exception. In no particular order - Labor, Liberal, the industry, environmentalists, bulk consumers - the details differ but all have engaged in some silliness one way or another.
On some of the specific technical and politics I'll add:
Batteries, running trains up hills, small pumped hydro etc all works fine if you just want to meet peak demand at 6 pm and find a use for surplus generation around midday and in the early hours of the morning. That assumes of course that most of the generation fleet has a reasonably consistent output.
In practice wind routinely gives us a week or more of high output and a week or more of low output. The lows in wind also just happen to unfortunately occur at the same time of year when total daily energy demand is high and solar generation is lowest.
Because of that we're not actually going to be charging batteries every day from the wind and solar alone. A lot of days yes but not all of them and realistically that gets us to somewhere around three quarters renewable energy pretty easily.
Where the ideological, political and financial battle exists surrounds the remainder. On one side it's the proponents of big hydro schemes as the workaround to multiple consecutive days when the wind doesn't blow, load is persistently high and there's not much sun. On the other side are those who wish to import LNG for use in both their own gas-fired power stations and those owned by others.
My personal view is that the biggest mistake anyone could make is demanding perfection in any of this and likewise it's a mistake to fail to acknowledge competing demands.
It's all well and good to get excited about hydrogen storage or whatever but the reality is that what's on the table right now comes down to pumped hydro versus natural gas / diesel so far as the means of filling in the longer gaps in wind and solar generation are concerned. There's no actual proposal to build longer term bulk storage using hydrogen or batteries as the technology so it's very unlikely to happen as the next step. It's hydro or it's gas / diesel in practice.
Related to that are the financial and political implications. If AGL, Origin, Energy Australia and others want to build (or contract others to build) smaller pumped hydros, batteries, wind and solar to work in conjunction with larger pumpd hydros (Snowy etc) as an integrated system well then that gives them a viable business role in it all. It ticks a box.
If big engineering things get built well then that's another group for whom a box is ticked. Not just actual engineers but civil contractors, members of the public who like seeing big "permanent" sort of things built, unions and so on.
If the gas industry wants to put hydrogen in the pipes, and that's about to start on a small scale in Adelaide, well then there's no reason to stand in the way. It keeps another group on side, it removes a potential opponent of it all and so ticks another box even if in an imperfect manner it's still a step forward.
If politicians can go around cutting ribbons whilst standing in front of big civil infrastructure well then that ticks another box. Make sure everyone who builds anything has the grand opening complete with ribbon and scissors.
And so on. Pragmatically there's more to it than just the engineering aspect of it all and keeping naturally conflicting interests reasonably happy is part of that.