I completely agree. Albeit at different degrees of severity, this kind of change impacts players of all stages - early, mid, late. Even veteran players rely heavily on ABs because of Zetas, Kyros, early relic mats, and Signal Data. Right now, it's only one AB, so the loss may not be that significant, but add those rewards up at the end of the year, and especially when more and more ABs start getting rotated, it's a big deal.
I for one don't mind new ABs replacing older ones, as long as the rewards are consistent and match what we are currently getting:
1) Compare the old ABs with DoF/PP, you see that the former has much more static rewards. Aside from the gear and maybe shards in the early tiers, the type and amount of rewards we get is the same each time - CT1 gives out the same amount of Zetas, each type of Kyro and each type of Injector piece every run, CT2 and 3 give out the same amount of early relic mats and signal data each time. Meanwhile, with new ABs, none of the tiers give out Zeta mats or Injector pieces; the first two tiers give you shards, but only for one out of the 2-3 required characters, nobody else; the later tiers give you relic mats and maybe signal data, but you only get one or the other for each type of material (one type of relic mat and one type of signal data); the last tier gives you either Droid Brains or Gyrda Keypads, which is something the older ABs didn't have (along with the R7-8 mats, but I'm focusing on the R9, since it's significantly harder to get), but one or the other means that it's going to take a very long time for us to not only get back the mats we spent to get the required toons to R9 but to also notice an actual RoI. Whether or not you should get the toons to R9, it's especially going to be controversial since, let's face it, how long until they release enough new ABs that even DoF and PP are put on rotation.
2) I also don't mind that much the relic requirements for the new ABs. Aside from the R9 tier, you kind of do need to have teams at relic levels to be able to survive in, let alone beat, CT2 and especially 3 (CT3 Sidious is an absolute monster even for relic teams). Okay, maybe lower at least one of the two tiers before it to R3/R5. But, again, make sure the rewards we get once the rotation starts are at best more than and at worst equal to what we used to get from the old ABs. Kyros, for example, right now only PP gives out Kyros (at a good amount), but, like with the other rewards, it's one or the other. Most of the old ABs, even the CTs, have been around for a few years, and because of that players depend on them as a consistent source of gear and relic mats. It's not exactly that surprising that out of nowhere we suddenly find out that those consistent sources of gear and relic mats are suddenly being replaced by newer battles with RNG-dependent rewards and significantly stricter requirements. It's not even that terrible if each new AB has different rewards, e.g., DoF gives out Signal Data (all types, not just one), PP gives out Kyros (both pieces), the next AB can give out Zetas, but in any case make sure they compensate for this new cadence you've come up with. Update the rewards in the new events if necessary so that, regardless of whether you're new, mid-game or a veteran, you feel like your investment toward the ABs are recognized instead of having to worry about it being invalidated after a few months.