I did not realise there was a bag drop in MEL. It is very easy to miss the signs. The walk from Int arrivals to Dom check-in is a longish walk when carrying 3 bags.
You must have missed the signs, it would have to be one of the shortest walks in any airport, straight up the travellator, which is about 30m from arrival exit point (or nearby elevator) and then another 50m to luggage drop from the top of the travellator. It's a shorter walk to there than to catch a taxi. Or as some have pointed out to the luggage drop area at SYD intl.
And
usually I am out and in a cab within 25mins of door opening at MEL, except if QF ground handling is involved (eg QF, NZ, etc). On the times I have been on airline that QF ground handling is involved then it often takes longer (the worst being a recent arrival on NZ, where we arrived 10 mins earlier than QF30 yet it was pretty blatant that QF30 was given priority over us as it took 38mins from door open to first bag

).
I admit it was the same story when I arrived in SYD last Friday from Singapore, but I did note that due to backlog at immigration (which I avoided due to APEC card), the staff had to remove bags from carousel as it was becoming jammed - with most pax stuck in the queue at immigration. So without APEC or express cards it would have been considerable longer.
I am not defending SYD Int-Dom connections but I still believe overall SYD airport is by far the best airport in Australia and the only reason I would use other airports for connections is to increase SCs and FF points.
Isn't the airport that is by far the best the one that is closest to your home, that means no or minimal connections.

For me MEL is the best, for you SYD for someone in Brisbane it would have to BNE.
Also in objectively looking at an airport you have to look at fitness for purpose. SYD is a hub airport with some intl (primarily NZ) and domestic connections - but domestic connections being by far the most common. It is also our "world" airport. On the intl connections - you need to look at parameters such as facilities (airside) which it does seem to be OK, but could (and will) improve. For domestic connections (inbound anyway) it is pretty ordinary by world standards as many can attest. One that does score negative points with me for SYD is the lack of an on-airport hotel. The Hilton is very convenient at MEL, as are the Regal at HKG, CP & transit hotels at SIN, Pan Pacific at KUL, Novotel at BKK, etc. The hotels at SYD are not so convenient (although at least the stamford and Formula One are walkable distance), and have poor frequency of shuttle pickups (at least compared to US hotels).
At the other MEL, ADL & PER are primarily domestic hubs and international "end of the line" airports (with very few intl->intl connections) so airside facilities not as important.