I couldn't fathom the havoc that a loose spare tumbling under the unit would cause. From just tearing things up to possibly tossing it on it's side, then as mentioned, anyone behind you would suddenly have to deal with a spare tire in the road, if they're not busy watching you crash.
I checked mine the other day, and it was fine. But I like the locking mod, for security and theft prevention. I might look into this little mod.
Now-2014 Sierra 346RETS 5er BUB
Then-2002 Keystone Springdale 286RLDS TT
Nights camped in 2014-28, 2015-127, 2016-10