Some further notes:
When it comes to icon-bearers and musicians, this has a very old-world warhammer fantasy feel to me. I don't really like the look of my guys going into battle with instruments (same reason I don't understand the bard class in D&D). That all being said, I definitely understood why they included rules for these things when AoS first came out. GW didn't want a whole bunch of models from WFB players' old armies to suddenly feel like they didn't have a purpose. Though WFB players for the most part were going to have a lot more problems with AoS than that.
But three years into AoS, having left behind Brettonians, Tomb Kings, and those pantaloons Empire guys, the aesthetic is decidedly not rank&flank, battle drummers, etc. Beyond just the feel of AoS, the rules have no real need for the unit upgrades either. Since they don't cost any points and cannot be taken out by a flanking opponent, the warscrolls might as well just say "X unit can add 1 to their run rolls" instead of "A unit of X containing any Icon A can add 1 to their run rolls" since there's no reason not to have those upgrades.
All in all I think it there are two ways this could go: 1) GW changes future warscrolls to simply have abilities rather than having them depending on whether or not the unit 'contains an icon bearer' etc. Or 2) they could leap frog the AoS rules system sometime in the future over the 40k one, incorporating a more involved point system like we see 40,000 years into the future. That could be cool, along with the new-and-improved Strength and Toughness system 40k uses. Though I think this option is unlikely.
Of course, the awkward 3rd option in the room is that GW keeps producing new model ranges for AoS that include unit upgrades which have no point cost/down side and are essentially auto-includes.
Gamer Glimpse:
-Hey see this guy with the skull on his base?
-Mhmm
-He looks like he's just got a sword and shield but he's actually also the banner-bearer
-Oh, okay
-And the musician
-Wow. Impressive
-Yeah. He's a great multi-tasker.
-G3