Hope you are doing well and it's great to hear some truths from other parents.
Well in my honest opinion
I feel that having listened to so many people and their different styles of what " perfect nighttime routine" is for kids is what made it take so long to find one. the perfect night time routine for your kids is one in which they receive the correct amount of sleep for their brains to develop and function optimally and well. The only thing I find to be the biggest disrupter for this is not always the actual time that they fall asleep but how they fall asleep and their emotional state when they do eventually go to Lala land.
In your case, that closure for them seems to be being around you or hanging out and if it does not bother you then enjoy it! these fine years go past so fast. and yes routine is important but there are many areas to practice it in and many methods to use.
So for us, we have made what gives them their closure at the end of the day the routine and in doing so they have started sleeping better and it's becoming less and less of a task for all of us. For our son, being tucked into his blankets and having his own space to make his car noises and seemingly never-ending soft chats with himself ( which have lately become rapping attempts.... pfff)
but in no time he is passed out on his own. For our daughter a whole routine of her own that requires a sequence of kisses and hugs from us and baby(Eskimo kisses, butterfly kisses, mountain bear hug, ear hugs and kisses...don't ask... and one more Eskimo kiss to seal (from all of us) tucked in than deal and lights out then she is out in 15-20 mins. Again, to be VERY clear that they never use to sleep well or early at all for so many years as mentioned by hubby 
Also, I must admit homeschooling now allows us that extra room for them to wake up later if they do sleep late but it also gives us the time to work when they are out much like yourself, but what fits one does not always fit another. I feel it's important not to set out to fix what is not broken only to best optimise and improve on it to best suit all your individual family needs if that makes any sense.
Take care and enjoy doing what works best for you and your family:-)
RE: Is bed time routine important?