So when people boast about Lucas Oil holding over 200 events a year, it's because Lucas Oil has outbuildings that can also be used as smaller venues that attract different things. I agree with you that 200 events a year is unlikely.
However, there are, likely, a majority of events that Cleveland would almost instantly get in the event of a new dome:
Major music icons
Super Bowls
Big Ten Football Title Game
Final Four Men's
Wrestlemania
Major Boxing Events
OSHAA championship games
NFL Combine
That's all just off the top of my head. That's an extra...25 events possibly a year? As opposed to that valuable lakefront property that gets used 10 times a year?
This is all without (selfishly) adding the benefits it provides the Browns. Better GameDay facilities, more butts in seats to provide better atmosphere, easier access to the stadium, no weather affected games. It's enough for me to not care one bit where the Stadium is built, just build the fucking thing.