Have the Cairo protesters read the new document? It is an improvement over the old one. If anything it is too ambitious, even liberal (in the classical sense of limiting the executive).
Or, is it being implemented wrongly? Morsi is accused of becoming a dictator for the transition period but no new constitution is welcomed by everyone. Even the USA required all kinds of tricks to overcome the anti-federalist opposition (e.g. it was developed entirely in secret while in Egypt it was all done openly on television).
Yes Islam is recognized in the document as it must be Egypt. (It has a broad social basis in Egypt; the demands of the protesters do not).
HOWEVER what Islam means exactly for Egypt and its political system NEED NOT be specified. Why not have a council of religious experts or Al Azhar advise on matters and then have the legislators, PM, and President translate it into policy? No need to foreclose options ahead of time. Taking pride in your heritage is one thing, ensuring prosperity is another.