No one is required to use it and even when you receive a mail tagged VSRE, you may still decide to write a long reply if you can not communicate your messag in

No one is required to use it and even when you receive a mail tagged VSRE, you may still decide to write a long reply if you can not communicate your messag in a few words. The obvious use case is you are communicating with someone for the first time or for not so long, you are fine with a short reply and you know that recipient would like to write a short reply but will not do so in order not to sound impolite.