I'd rather keep them on NXT, considering WWE called up 12 people at least since the beginning of the year and here is what happened.
Heavy Machinery: Reduced to comedy fodder which they may be comedic, but they aren't presented as serious competition.
Lacey Evans: Getting a Women's title match, but was inactive in matches and feuds for the Wrestlemania build, including being off the card, and at most being a mute troll.
EC3: At first was a mute male stripper essentially despite his talking ability being one of the best things about him. Had a pointless win over Ambrose but most recently was chokeslammed through a stage on RAW last night, presumed dead, or at least, six-feet under.
Nikki Cross: ... Had a few moments to shine but considering no sense of if she is face or heel (BECAUSE SHE IS CRAZY, LOL) and has yet to have something to sink her teeth into.
Lars Sullivan: Debut was delayed due to real life circumstances and got off decent by laying out some legends, so we will see with him.
Tomasso Ciampa: Got injured, but he at least had a couple of nice matches teaming with Gargano... Despite it essentially not coinciding with ongoing NXT Storylines.
Johnny Gargano: See above, has since returned to NXT and become NXT Champion, breaking Beavie's scale with his title match and some lame person named Meltzer.
Aleister Black: Nothing special yet, minus being put in an odd team with Ricochet which has surprisingly done decently... But at least he got to have a great match at Mania. Michael Cole called him... moody.
Ricochet: See above. Michael Cole says "He's fun to watch!"
War Raiders: THE VIKING FUCKING EXPERIENCE AND THEY GOT NAMED IVOR AND ERIK. NAMES SO BAD, IT DROVE ME TO ALCOHOL AND THEY HAVE BECAME AN INSTANT MEME! AND NOT A GOOD MEME, I MEAN THE "THIS IS STUPID AND THUS I WILL MAKE FUN OF IT!" MEME
So, several people reduced to mid-card, and some people doing okay... but others like EC3, Heavy Machinery, and Nikki Cross have been near invisible with no plan, and then Lacey who is only doing something now. Then two people who essentially went back to NXT. This is why fans who follow them in NXT have gone from being excited about people being called up to outright fearing it. Remember the Half Time Heat match? Corey Graves asked why "Velveteen Dream wasn't on the main roster" and it caused fans to lash out? This is why. Either they are called up with no plan, or are now in a growingly crowded roster fighting for TV time, or their NXT history is ignored and they are changed on the main roster before we can see whether or not they're working. And you don't need to perfectly keep every single bit from NXT, but this isn't FCW, OVW, or Deep South Wrestling where most fans don't see it. This is a show which has essentially become a hybrid of a developmental territory and a third brand, selling out arenas the nights before your biggest PPVs and has even some casual fans taking note and being impressed by them. Plus WWE's main roster is in a weird place where they are crowded and people aren't being used, but the same people are being overexposed and losing their lustre (or falling in Baron Corbin's Midcard Vortex of Evil).
Undisputed Era being called up may lead fans being worried about them having their names reduced or the stable being called "The Indy Experience!" with their gimmick being changed in a way not for the better, or being like that Sanity was and invisible.