It is actually not very uncommon IRL for helicopters to land on the road. In some countries, some first-response air units are actually specifically trained to land in tight streets.
We have always been allowed to land in the street.... and what about the helipad on top of the SAHP then??? It's not even a flat surface for a helicopter to land there safely, and IRL the roof would probably collapse with the weight of a helicopter
The city is already very criminal-sided, let's not make it even harder for LEOs to do their jobs. SAHP is far away from the city, and helicopters allow us to assist FIB and LSPD faster. Not just for globals, but also to assist during store robberies.
Search in Google Images for first responders landing in the street and you will find many images... this is not fail RP.