He would've suited well in Allegri's system but if the intention was to make us play a more attractive brand of football, than swapping him for one of our most technically gifted footballers wouldnt have made sense.
Even signing him not at the expense of Dybala would have caused a lot of tactical headaches and we probably wouldn't have seen the best of Dybala like we've witnessed this season.
The more I´ve seen of Lukaku in Italy, the more I feel maybe he wouldn´t have been as bad of a fit in Sarri´s system as I thought. He´s technically limited, but he´s so strong he creates space for himself with several opponents on him, which allows him to play people through in tight spaces. He´s got great stamina too, the guy presses like a maniac, which we also miss.
In terms of Dybala, Real used to play Isco in this free role on the right next to CR and Benzema and he flourished. Mainly because Benzema was so good at creating spaces for others, and I think Lukaku could´ve done something similar for us (not to Benzema´s level of course).
Also, compare all of this to what Higuain has given us this year, CR and Dybala would always struggle with his useless contribution in that 9 role. No pressing, no spacing, no headers, no focal point at all. Anyways, let´s see if Milik can do the job or whoever the new striker will be.