Well yes, actually!
At my small village primary school (many years ago!) we were all taught LM and LD in the traditional way, understanding as much as was needed (based on the THTU structure of decimal numbers). The technique was instilled, and like so many techniques learned at an early age, became second nature. No, I cannot work out square roots in my head, because I was taught that technique later, but there again I rarely have to calculate the square root of anything.
Then you (and your classmates) must be one of the brighter ones at it. At all the schools I taught (which are by no means low achieving), plenty of 12 and 13-year-olds struggle with it.
But none of that is important.
The central issue remains the question I asked earlier. What skills are we teaching them through long multiplication and long division? What objectives (among the ones you gave above) cannot be achieved through a better understanding and application of estimate skills (which are far more important and useful)? Why should long multiplication / long division be made compulsory over other methods to perform manual calculation, many of which far more intuitive than these ones?
As it happens, I struggled with LM at first, so I was certainly no maths prodigy. In later years, however, when sitting Accountancy in the AIB, I was not completely sunk when the calculator I was using began giving random answers because of low battery. If you have never had a phone that has failed, you are one in a million.
That has no relevance to the world we live in today. Are we teaching them long multiplication / long division to perform better in exams, or to give them essential life skills which they can use?
How often do you find yourself in a work/life situation these days with all calculation aids died out and needing to perform high-precision calculation, with no access to any help whatsoever?
I would even go so far as to say that if one needs to perform long multiplication / long division on a regular basis in a work environment, not using a calculation aid is stupidity, as time wasted on doing it manually can be better spend improving productivity in other respects.
I don't agree with it being made compulsory that long division and multiplication are the only ways that children should be taught to multiply and divide, but I do agree that it should be taught alongside a range of other methods and children should be allowed to use the method they prefer.
That I absolutely agree with.
Children should be taught various skills - diagonal method, line method, point method, box method, etc. Some find certain ones easier and others find other ones easier. They all serve the same purpose, so why should it be compulsory that everyone be judged against the same prescribed method, which for all purposes can be argued to be something with very little practical use in today's world?
There's a more efficient way than either of those:
I knew some clever dick will find a better way, but you see my point. There are various approaches.
Maths isn't actually all about the numbers/answers as I suspect you know

Over reliance on calculators doesn't make you numerically literate - which is really important for, for example, understanding statistics (probability, polls etc.) and finances (savings, loans, discounts etc.).
I agree, that is why estimate skills are so important. It gives you a sense of proportion, size, and helps make it possible to make quick and informed decisions.
I am not advocating complete reliance on calculators (indeed that would be completely wrong and counter-productive), nor am I saying that manual calculation methods should not be taught. I simply do not agree that one particular method which sees very little practical use in today's world be give such prominent status.
And the ability to solve complex puzzles and analyse problems is a pretty vital skill for most knowledge workers.
There, my friend, you have nailed one of the biggest failures of today's mathematics education in the secondary and further education sector, and has been for a great many years. Mathematics has very little to do with numbers, yet very little emphasis is placed on teaching students how to approach problems and analyse them, how to break a question down, how to construct the arguments they use in a logical and coherent manner, etc.
The standards of some of the freshers are truly shocking (but obviously standard vary with some who are very good), even those who got A's at A-Level. Plenty of them cannot string together a couple of coherent arguments, and plenty cannot recognise a question if worded or presented slightly differently. Every year we end up spending the first few weeks re-teaching them the most basic things they should have learned and remembered, and should be rolling off the top of their head. Did their colleges train them to answer exam questions (which they would inevitably forget once the exams were done), or did they teach them how to dissect a problem and understand it?
Someone I know has a calculator that has a percentage button and lets you type things like 100 + 20 %, which would yield 120. Rather confusing syntax if you ask me, but apparently its intuitive.
Cue her turning gross prices to net by typing 100 - 20%, and not being able to understand my explanation as to why this will subtract the wrong 20%.
You'd be surprised how many people don't realise that adding 20% then subtracting 20% will not give you the same number you started with.