Do it. If you leave the UK for >2 years they can decide to revoke your IDL (which makes the name a farce!) and not let you back into the country. Also, you do not know what you may choose to do in future.
I was borne in Devon so have British citizenship, but my folks emigrated to NZ when I was 10 months old. 27 years later, with NZ permanent residency (the equivalent of ILR) but not NZ citizenship I came back here. 7 years later I’m married to an Australian and we want to move to Australia to raise our soon-to-be-born son, but I am waiting on a visa which will determine whether I’m allowed to enter Australia. Had I got NZ citizenship I wouldn’t have this issue and would have saved myself approx £1000.
In the long run, citizenship is by far the better option. Do it. You may only live to regret it later.