Apparently, there's no difference between 400 ping and 100 ping, as the game works in 500ms intervals so the effect of ping only changes with 500ms intervals; so ping would have to be over 500 to appear any different to any ping below 500.

However, ANZ players with pings decently below 500 constantly get kicked from matches with the message "Reason: Ping" by European hosts, presumably with the logic "They're on the opposite side of the world, they'd single-handedly ruin the ping for everyone else".
And while it is true that we're on the opposite side of the world to Europe, it doesn't matter, unless somehow the ping does actually get above 500 (which would require unusually bad internet)

So, could we have a loading screen hint that mentions that unless someone's ping is showing in the lobby, ping has zero effect on gameplay?

I actually kinda hate the style of matchmaker maps and they are indeed very noob unfriendly.
The issue with them isn't the start though, it's that they're micro-heavy: Mexes all over the place and with almost no terrain obstruction to unit movement meaning that you can have as many lines of attack as you're capable of managing and your opponent has to be able to keep up with defence.
Making FAF micro-heavy is kind of like blitz chess: On the one hand, it's a great challenge for pros. On the other hand it completely ruins the experience for a lot of people.
Ever noticed how the most popular noob maps are ones that force the game to be played in such a way that you can play with really low APM and still win by virtue of strategy alone, by severely limiting the lines of attack and assigning many players to manage them? Though they often do this to too extreme an extent and players don't step out their comfort zone.

Okay, this idea is probably totally broken, but imagine this:
ML loses 10k health but gains a 10k area shield for protecting nearby units.
ML still only has personal stealth, but it can project both cloak and stealth to nearby units (at a huge energy cost).

Essentially, it's still a trash experimental on its own, but a ML fielded outside of omni range is a complete wildcard and you ought to send a T3 scout every so often to make sure it's not up to anything.
It'd be pretty hilarious if someone fired a Billy at a ML hiding a loyalist.

Kind of an out-there suggestion that I doubt will be seriously considered, but it could be used to stretch out the relevance of ground experimentals.
Rather than making the experimentals simply better through increased DPS or health, the experimentals are made into much more versatile units.
Here's some ideas for what this could look like:

Fatboy:
Slot 1: Air factory | Improved engines
Slot 2: Advanced AA (aircraft carrier grade) | Tactical Missile Warfare System (equivalent to four TMLs and TMDs, builds TMs with reduced price and damage and scatters when launching a volley)

Galactic Colossus:
Slot 1: Disruptive Beam (beam has increased shield damage) | EMP Overcharge Cannon (manual/auto fire like ACU overcharge, requires a huge amount of energy to recharge)
Slot 2: Rapid Reclaim System | Rapid Capture System (tractor claws reclaim/capture units at a very high build rate)

Ythotha:
Slot 1: Incendiary AA Artillery | Portable Gateway (moving units to Ythotha teleports them there at the cost of energy, with enough energy you can even move experimentals)
Slot 2: Amplified Detonation | Tactical Nuke (Like Billy)

Monkeylord:
Slot 1: Stealth field -> Cloak Field (no self-cloak) | Stationary Fire (improved range when not moving)
Slot 2: Bubble shield | Radar Jamming

Megalith:
Slot 1: Flak Battery | Long Range Missile Deflection
Slot 2: Artillery Guns (similar to three gunthers but with 100 range) | Advanced Engineering Station (equivalent to two maxed out hives with double range)