Antenna flexibility?

How flexible is the base of an intact OEM antenna?

The rubber on the base of the antenna on our 2007 is mostly cracked off exposing the spring so I bought an inexpensive replacement:

US 16" Roof Mast Whip Radio Aerial Fuba Antenna Fit for 2003-2008 Toyota Corolla | eBay

It is the same size, screwed in without problems, and the radio works the same. However, the base is not very flexible. It will bend a little with a lot of force but if there is a spring in the base it is very, very stiff. If I push down with a finger near the top of the thick boot at the base it will flex a bit but so will the car roof. Conversely the broken antenna was super flexible and in the same test it would just fold down flat with the roof easily. However, since there was no rubber around most of the spring, I cannot tell if it is more floppy than an intact one would have been.

Edit: by "base" I am referring to the fat rubber part of the whip part of the antenna immediately above the screw, not the "antenna base" which is firmly attached to the roof of the car.