Feels to me like Australia's success has often been due to a few batsmen. It wasn't that many years ago when it felt like it was Clarke and Hussey at 5 and 6 bailing out a changing cast of top and middle-order batsmen. And in recent years it has more often been Smith and Warner bailing them out (seriously, IIRC Smith made 1,000 Test runs at a 70+ average 4 years in a row...). And looking back at the 2017 Ashes draw in Melbourne, it was those two along with M Marsh who did the majority of the final innings batting. Obviously we haven't had them this year, haven't been able to replace them, and I haven't seen anything suggesting they won't be rushed back into the team the instant their bans expire. A stronger team would be able to make them prove their fitness to be selected.
I've found quite a few of the selections odd: Finch has done lots for Australia with the white ball, but over the years he's struggled even to make Victoria's red ball team. He was better in the last couple of years, but not set-the-world-on-fire better. Plus he was mostly playing in the middle order for Victoria - why pick him as an opener?
Coming back from the UAE as incumbent, Mitch Marsh was dropped for the first couple of Tests. After being dropped he played one first class match and one T20, didn't do much in either, and then got picked again in part as a bowler. Last year in the Ashes he held his own as a batsman, and it would be great if he could continue to do that. But I'm not sure there was anything in his performance to justify the recall.
And, with Labuschagne added to the Sydney squad, I'm afraid the same will happen again. His leg-spin was certainly useful in UAE, but he was presumably dropped for not doing enough with the bat, and he hasn't done enough with either bat or ball since to justify selection.
And then going a bit further back, some of those who didn't make it through selection. Glenn Maxwell coming back relatively successful from India/Bangladesh, then dropped for the Ashes, rushed to South Africa, but not even making the squad for a UAE tour. Joe Burns rushed over as replacement opener in South Africa, then overlooked (just from a process point of view, both Burns and Renshaw are actual first-class openers, and for that alone deserve more consideration than Finch for an opening slot).
Anyway, I don't guarantee to be a good armchair selector, and there may be more context here that the selectors are aware of and I'm not. And like always, when it comes to the actual Test I hope the selections I'm skeptical of perform and prove me wrong - like Shaun Marsh did in the Ashes 2017/18. But Australia is meant to just win at home, y'know?