All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
We do not know of any objection based on the Sharee'ah (Islamic law) as far as having some umbrella over the Ka'bah is concerned. However, we think that this question should be addressed to those in charge of the Masjid al-Haram. They might have some reasons for not doing so.
Allaah Knows best.