I think people just need to chill out a bit when it comes to Lukaku. He's having a very poor season so far and looks bereft of confidence, but he didn't start last season particularly well either (in terms of general play) but masked this with a pretty good goal scoring record. His overall play massively improved from around February/March onward and he ended up bagging 27 goals - not bad at all for someone who's been likened to Emile Heskey in this thread.
It's easy to fall into the trap of using today to demonstrate that he interrupts the flow to our football and that Martial and Rashford ensure more fluidity, but there have been a number of occasions where these two have been given a chance to spearhead our attack (or one of them get a start on the wing) and they've largely disappointed, with the team looking completely disjointed and anything but fluid. I was delighted with Martial today and hope he can start to gain some consistency, but to say that either he or Rashford would offer more than Lukaku over an entire season (at their current stages of development) is madness. We looked more fluid today because Pogba and Martial were both at the top of their games, rather than it specifically being due to Lukaku's absence.
This is indicative of recency bias - it seems that every time a player goes through a bad patch of form then they're suddenly not good enough for the club.
Also, can somebody explain why some keep saying that Lukaku needs to score 25+ Premier League goals per season? Ruud Van Nistelrooy, largely considered to be one of our greatest ever strikers, only managed this feat once, and in that season (02/03) only 13 of those 25 came from open play, with 12 from the penalty spot. Not to mention the fact that he was in a team with much more attacking talent and nous than the current side (at least for his first two seasons) and was working under an attacking manager to boot.