Not sure why anyone finds it surprising that Lukaku gets a shit ton of stick.
No matter how he was playing, he was usually the first name on the sheet under Mourinho. If we gave Martial or Rashford a random chance up front and they didn't perform well enough, they were hung out to dry by Mourinho as he was happy to use it to tell the press to mind their business as they had feck all knowledge about football, like his "now you know why Lukaku always plays" reference. Add in Lukakus interviews, which was him bigging himself up, talking about his mentality as being rock solid, being willing to run through a brick wall for Mourinho and that's why he's a favourite, that players need to grow up and be a man, to deal with their own shit with Mourinho. People started viewing him as a teachers pet, and rightly so, with his performances being nowhere near good enough to warrant the preferable treatment he was getting. Factor in his comments about Juventus and it's hardly a surprise that he's not the most loved player at United.
In terms of his form now, no idea what's going on with him but it's blatantly obvious that he's in a shocking state at the moment. It was pointed out quite early that something didn't seem right, he looked heavier, but it took ages until people were willing to accept that he had gained muscles, Lukaku himself confirmed that later on, but we're well past the point where he should've been able to trim it down. The various clips of him letting the ball bounce instead of trying to control it reminds me of childrens football, it's the very definition of a "what the feck" moment when you see a professional footballer on more than one occasion lets the ball bounce to make it easier to control, the worrying part is that even then he fails miserably, often being outmuscled by players half his size and/or mistiming the header after the ball has bounced.
More worrying is the fact that he looks lost, he can come on in the 70th min and 5 minutes later he looks like he's been playing for 100mins. Lack of runs, often standing still, doesn't look like he's anywhere near finding his form again. It's not like i think he has a long term future at the club, but short term it would be extremely valuable to have an in form Lukaku as an option, especially now that we have a great chance of knocking out PSG and finishing 4th.