Within the UK, many different accents and dialects exist. Received pronunciation is often referred to as the Queen’s English or BBC English which is estimated to be spoken by approximately 2% of the British population.
Some would argue that RP is outdated but this couldn't be further from the truth. In fact many aspiring British actors learn RP at acting school and it is spoken by many famous and notable people within the UK. Checkout these Pinterest links to get an idea of British people who speak RP in some form or another. For any speaker of RP who might come across as a bit pompous, this could be due to their use of voice inflection and intonation rather than the accent itself.
Some would also make a distinction between traditional, upper, neutral and modern RP. For example, perhaps the younger members of the royal family such as Prince William could be considered to speak with a more modern RP accent.
There is no "correct way" to speak English, however received pronunciation would be suitable for non-native English speakers since it is clear and tends to be easily understood by people around the world. Those who need to communicate clearly and effectively such as diplomats, business men, interpreters and scientists would probably benefit from learning RP.
More information about what Received Pronunciation is can be found here: https://en.wikipedia.org/wiki/Received_Pronunciation