That last bit is the kicker. As a hangover from the amateur era, in many ways it does make sense that they've done away with the 'A' concept.
I cast my cynical eye with a grudging approval at the way the Kiwis seem to be doing this now. Leaving aside the Maori All Blacks, which is a different thing, you don't really see the "Junior All Blacks" (NZ A) much any more.
What they do instead is include some fringe squad and emerging players into the full All Blacks side to play Test fixtures against the likes of Japan and the USA. It's commercially marketable but also gives new players opportunity.
There are a few holdovers from an amateur era. "A" teams are one of them. Tours are another. BILs are another. A growing minority believe the latter now simply exist to prop up the Southern Hemisphere Unions. A different group think the domestic tour games are nonsense, and would be better served playing other Nations. I don't agree with the former, I have a growing appreciation for the latter, and I do understand the view. It's a holdover from an amateur era that does damage the performances and brands of Clubs and Nations.
Conversation for a different time however. I reckon "A" sides need to be removed, revamped or given greater incentive.
There is an inherent advantage to the sides that choose to nominate the U20s as the A Side. While it does weaken the teams at this level, with some players choosing not to commit, more often than not they do, and it's far more financially feasible than running an A Squad.
But for teams like New Zealand and Australia, where so many players turn out for players of their heritage rather than birth, or been raised in, to do it that way is to deprive them of an opportunity on the national stage.
I'd do the double up. Some incentive is needed for A teams to become active, and in ideal circumstances, playing teams outside the old Tier 1/2 ranking system. Uruguay-Brazil-Chile, Namibia-Zimbabwe-Kenya, Russia-Spain-Portugal, etc. What that is I don't know, but it really needs to be so for development purposes.
Plus, I'd switch it to a Football system, whereby being capped for a non-senior team simply rules you a) eligible for the senior side in perpetuity and b) unable to gain new eligibilities through the process of residency. Increase numbers though. U20s, plus up to another 4 nominated open age squads, at either 7s or XVs.
Ah well, ramblings of a ninny.