This Aviation Week Articls (Paid Subscription Required) mentions a number of issues and complications:

• That any decision on a ground assault would be influenced by the outcome of PA/Israeli negotiations.
• The article implies that a failure in negotiations would lead to a ground action, but I see it as being the other way around. As long as their fingerprints are not on it, the PLO/Fatah would love to see the IDF assaulting Hamas and Islamic Jihad, they are their rivals.
• The high population density makes operations difficult.
• The tunneling operations can reduce the utility of air assets significantly.
• Uncertainty as to the actual size of the opposing force.
• FWIW, I think that Hamas is uncertain of this too. Much of the goodwill that they used to win in parliamentary elections has been exhausted, and so it is unclear how many of their irregular forces will take up arms if directed to do so.

As the joke goes, “Yes, but this is the middle east.”