How come with the world's best weapons, about $1 million of US in weapons funding for every one of the 20,000 militants, a year of fighting against a militia with no heavy weapons who are all trapped in an area the size of the Isle of Montreal, Israel hasn't been able to defeat them yet?
The end result is more important than how long it takes to achieve ones goals.
Let's see:
Hezbollah ran away and abandoned Hamas.
Hamas is isolated with no one at all supporting them.
Iran is afraid, weakened and ineffectual. Those 300 drones got swatted away like flies and the US is watching their every move. Israel killed Hezbollah leaders in the heart of Tehran with impunity.
The IDF has Hamas surrounded.
Out of their original 24 battalions only 4 remain.
Instead of asking why is it taking so long, the question is how much longer can Hamas possibly survive? How many more Gazans must die so that Hamas can continue to fight an unwinnable fight? How long until the people of Gaza overthrow Hamas? These are much better questions, Geno.
Or, if you want to stick with your original question, it's taken this long because Israel knows that the eyes of the world are upon them, so they've had to do everything in their power to minimize the Gazan deaths even though Hamas has left them exposed and used them as human shields. As NAD has pointed out, the fact that only about 25,000 civilians have died (according to Hamas controlled agencies) is a testament to how careful Israel has been.