Hiya, thank you so much for your question. the truth I am actually strictly adherent, all my 'liberal' views comes from strictly following Islam!
you are definitely right about the culture! many people follow Islam (and other religions) without understanding it or connecting to it on a different level. so for them, it would be joyless.
the actions you describe are those which are externally visible, but it's a bit like an iceberg... there has to be a lot more to it on the internal being of the person. sadly many practice the external rituals without the internal aspect.
as well as culture, there is the global pandemic of salafism spread with Saudi oil money. this is a sect developed in the early 1900s by an Arab warlord (who was not an islamic scholar and was in fact declared a heretic) who was armed by the British to fight against the Ottomans. this Arab warlord then established salafism in Saudi and spread it through the world and eventually leading to Alqaeda/taliban/ Isis etc. this sect is pervasive in East London. else where in the world the older version of Islam can still be seen eg in malaysia/turkey etc. salafism is certainly joyless as it only external ritual and rules without spirituality.
music is certainly not forbidden! there is a lot of islamic spiritual music (maybe listen to abide parveen, nusrat father Ali Khan on youtube?). it has actually been one of the ways Islam was spread in India
fasting looks ardous, but as any person who fasts will tell you, it genuinely brings immense joy. it is not like a normal day of going without food, you don't feel it in the same way. sexual acts outside of marriage are forbidden, but individuals are encouraged to speak at length prior to marriage and marriage is encouraged. as someone who was not so practicing before and has dated, I can tell you I really don't feel like I am missing out and practicing Muslims don't either. because we view relationships very differently. same with food restrictions etc.
of course if you are used to living life in a certain way, our way of life looks restrictive and I understand that. some Muslims even might find it restrictive and can lapse, we are all only human.
BTW East London is certainly a microcosm. it doesn't even represent the culture of Bangladesh/Pakistan! if you wanted to experience a more representative islamic vibe, I could recommend a few ideas?