the only reason I can see for removal is if you are only interested in maintaining a small fighting force for GEX and are not participating in GBG anymore
Current age units are not hard to get. If the game is going to be current-age-focused going forward, no one needs Alcatraz. I've done GBG since the beginning of it and only ever briefly built current age barracks to get initial troops when aging up, but by SAJM I didn't even need to place barracks. I have thousands and thousands of SAJM troops and none of them ever came from Alcatraz.
The whole point of Alcatraz was to make stocks of rogues (not so crucial to have in space ages or with 4000% boosts any more) and to be able to maintain a stock of 14 different ages for GvG on multiple age maps, without having to have all the barracks in your city at the same time. With gvg and multi-age fighting removed from the game, there's 0 use for Alcatraz, and they just keep releasing more special buildings that make all the various troops for you.
Bullion garrison makes artillery in 1x1 plus a bunch of other stuff
eden airship makes 3 fast units a day plus other stuff
stage of ages makes 12 ranged units a day plus goods and fps
cider gardens make 1-5 light units per day plus boosts and other stuff
racoon hideouts make rogues
then there's all the special stuff from the last year that makes random troops - donkey enclosure, sheep shire, panda reserve, knights pavilion, governors villa, winter pyramid - and all those buildings also provide goods, fps and or attack/def boosts along with the troops.
Oh and I forgot the egypt settlement reward that now makes 20 troops, plus all the emissaries - I could be getting 30+ troops per day just form my town hall but I prefer the goods and fps since I have troops coming out my ears already.
They completely negated the need for anyone to touch the barracks in the standard build menu, let alone keep an Alcatraz. After they announced they might "make some GB's relevant" again it has given me pause, but I'm just about pissed off enough / stopped caring (since they released so much overpowered stuff into the game that nothing really matters any more) to the point I'll probably delete the giant eyesore that is Alcatraz before much longer. I just wanted to stock up on a few things, but really, I'm not sure the point of even doing that now.