Oh, sure, I mean, "complicated" in that it sucks.
Playing in a publicly owned outdoor facility where the revenue from other events goes to the city/county/state rather than the team isn't super uncommon in the NFL, actually, but it's not the way the state of the art is moving, and the combination of Soldier Field's other weaknesses as a facility and the massive value of the franchise's monopoly on NFL football in the Chicago market make it a situation the team is quite obviously trying to change.
Arlington Heights is too far away. It's farther from the central city and sits amid more low-density suburban development than any major pro sports facility in the country. BUT, the Arlington Park parcel of land is absolutely perfect for this sort of project and while the overall traffic/transit connectivity isn't ideal, the existing Metra stop on the property is a pretty big plus. It's a risk, but you can see why the team believes it has brighter prospects out there.
SoFi Stadium is the new hotness in the global sports business, and the Bears not unrealistically think they've hit on the opportunity to build their own.