I already did it twice on my motor because I ride often in the wet. I didn't yet replace the seals because they were still in good condition. I only removed the old grease and dirt, and then re-applied
a lot of the Bosch grease according the procedure which came with the set.
On the gen4 motor the sealing is mainly done with the grease which is trapped between the seals and bearings. When the grease is gone or mixed with water, the sealing didn't work anymore and water can ingress into the motor.
I think it's worth to do it. The set costs nothing (around 20€) and there is enough grease to renew it 2-3 times.
The set from your picture is not for gen4. This is the one for the gen4 (with two external securing ring):
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