You never want to point the antenna at the plane. ALL antennas (of this type anyway) have a null straight "up". 72 mHz, 35 mHZ also have that problem. In the old days before we had "no code hams", we all learned that for VHF/UHF operations
People have a natural tendency to point the antenna at the plane. "Bending" it 90 degrees makes it pretty un-natural to do that.
I haven't seen any RF studies that show 90 is better than anything else (but I bend mine at 90 when it comes out of the case anyway)