What is needed is an option inside WLM to the effect of "Minimize/close WLM to system notification area" which could then allow the older behavior without the need for a "hack" like compatibility mode.
I'm personally really dissapointed with this new behavior; I think the Live team missed the memo about the Superbar being designed to be more intuitive and less cluttered... The new behavior looks more like a bug than a feature, and many users will see it as an annoyance.
I think the biggest problem is that the Beta and RC phases aren't being tested with the "common" demographic; Is the the 68-year-old grandfather that knows very little about computers going to try the beta? Unlikely. This (common) demographic is one of the ones that have the most trouble understanding computers, yet use applications like WLM most often to keep in touch with friends and family.
The Live team willingly decided to make their application appear to "misbehave", which will be overly confusing to people that don't follow the latest technology. Perhaps they'll hear the outcry of complaints (or more likely, will but won't care) but until then, it'll be up to us, the "power users", to "fix" this oddity for them.