So, are there any advantages to using rigid RF coaxial cables?
First, the product you show might be semi-rigid rather than rigid cable.
In either case, the main advantage is lower loss, because of the solid outer conductor (as compared to the braided o.c. used in flexible cables). The solid o.c. also reduces radiation, which can be important if there are sensitive receivers nearby.
In a production environment the rigidity of the cable is itself an advantage because it means the system will always be assembled with the cable arranged in the correct way, rather than however the assembly worker can make it fit. The rigidity of the cable also improves phase stability.
Most of the disadvantages you cited can be mitigated, or don't even apply when manufacturing in volume.
Limited in available angles 45° or 90°.
Not true at all. There are numerous shops that will bend these cables to whatever angles you like, following your drawings.
Sold in sections so we may need to always join them
Not true. You can have these cables assembled at whatever length you like.
Certainly they can be fabricated up to at least a meter in length, which is plenty for the type of system you showed in your image.
Prone to corrosion
The outer surface is typically tinned copper or aluminum. Either of these materials is likely to be present in numerous other locations in an electronic assembly, so these cables will be no more prone to corrosion than, for example, the surfaces of any PCBAs used in the product.