Russia will in the near future start with taking out many missiles. It is much more economical to have one missile with 10 warheads than to have 10 missiles with 10 warheads.
As to why they build new submarines, they have to try to recover from the blow they got after the break-up of USSR. They won’t use it, but it’s a cheap way of keeping off possible attackers. You don’t have to maintain 700 ships if you have some nuclear missile armed subs. Now they have both, but it’s cheaper to get rid of the old ships they have now.

UK is planning for a new SSBN class, but have trouble with this issue in their parliament.

As for US, If US was loosing its silence advantage, they’d be doing the adverse of what you are saying. They’d not want these short-rangers, as that would involve going closer to your enemies. They’d want longer range, and probably surface launch capability too, as that allows you to stay in your nice and safe harbour and still be able to launch.

It seems that U212 (and hence possibly U214) is using a weapon called Barracuda… Supercavitation with an ingenious steering system and a speed of 360km/h (approx same as Shkval). Developed by Diehl and Atlas Elektronik. Although it should be said that no answers are officially given to the question whether U212 has this weapon.
Nonetheless U212 is a better submarine with the heavy new torpedo (and possibly this supercavitation weapon). I think they could negotiate to receive these weapons as India doesn’t directly pose a threat to Germany.
And also the offer with the Russian Klub incorporated sounds appealing, much better than the Scorpene.

Great pics there darling.