Not sure who you refer to in the "...we have already made a decision...". You mean SKiCAL? I can't recall that the IETF calsch WG didn't make such a decision; or that such a proposal was actively discussed. I think we were still waiting to hear what the complete requirements were. The specification you posted is an implementation profile, but doesn't really define the problem domain requirements. Right?
Back to the requirements...For an event, such as a Boston Red Sox baseball game, I can certainly see that it would be beneficial to have an additional property in the VEVENT definition that indicated when the gates opened. Very often, public events have both a
-- Frank