#4 The better possibilities
If WWE is bringing back Goldberg for a big match, why should they do it with Brock Lesnar? Yes, it is a mainstream draw, but from a wrestling standpoint, there are better matches that WWE could make.
Lesnar would struggle to carry around a 49-year-old Goldberg but someone younger like Seth Rollins, Roman Reigns, or Kevin Owens would do a better job.
A match like Goldberg vs. Roman Reigns is more appealing to the current fan base as we have already seen what Goldberg and Lesnar could do when given a big stage. By having such a booking, WWE could have two big draws separately on the same card.
Brock Lesnar versus an upcoming star and Goldberg versus another upcoming star on the same card; think about how exciting that would be.