Sorry Skywalker I disagree.
What you have made is a statement based on your own attitude to risk and this is not enough to pigeonhole every other person who may want to look at different rates.
Each and every person will have a different attitude to risk which is often dictated by the budget that they have available and if the budget is close to maximum affordability then most likely the fixed rate may be the best option, but quite a few of these people may still feel that other rates would offer a more cost effective repayment but threatens a risk for soing so.
While a fixed rate does give a guarantee of knowing what your payment will be for the next 24/36/60 months it also offers a pretty cast iron guarantee that you will be paying more than someone who has taken a variable rate mortgage and this is where the attitude to risk come into play.
If you were paying a fixed rate of £500 per month but could get a variable rate for £450 per month would you want it if you felt interest rates were not going to move for the next 2 years? over 24 months it could save you £1200, thats lot in anyones book. If it was over 60 months its £3000. You stand to take the risk that rates won't go up but in most cases now the variable rates are about 0.50% cheaper than fixed rates and so that means (most likely) 2x interest rate rises just to break even with the fixed rate products, and as most analysts (who generally set public opinion and not get shot down by it) think we have quite a while before interest rates rise (they have been right for the last 18 months) it would mean that overall a varibale rate mortgage would definitely be the choice to go for as it would mean that interest rates would have to rise by 3 rate rises in the first year to make it less cost effective than the fixed rate. If you are looking at longer term fixed rates then the difference between variabnle and fixed rate could be 2% - 3% and thats going to make a big difference on anyones mortgage repayment. Of course it also has to ne noted that there is no cap on most variable rate mortgages so the sky is limit so far as rate rises and how high a variable rate mortgage can go.
However. All this is a moot point if every single person on the planet opted for a fixed rate because it gave a guarantee that you had stability and could budget...soon the new fixed rates products would rise in cost to fill bankers pockets and the variable rate would then become very attractive.
Its all about attiftude to risk - Either you get a cheaper product but run the risk of rate rises and (potentially) losing money or you don't run the risk but know you will pay more for your rate right through until the rates rises (if indeed they do)
Just because you feel safer with a fixed rate does not mean that everyone else will feel the same way.
So far as being able to overpay on any particular mortgage. nearly every single mortgage on the market has the facility to over pay by at least 5% of the outstanding balance per year and more often most lenders will allow 10% of the outstanding balance per year but the thing is that most of the people who would take a fixed rate on a purchase mortgage would be right at the maximum of their affordability and so the likelihood of them actually making an overpayment on their account is extremely low. It is very rare for any mortgage I have set up for anyone where they have intentionally overpaid on the mortgage because quite franly most people will think of 1001 other things that they would rather spend their money on than the mortgage.
But as it happens I 100% agree with you that the priority should be to clear the mortgage as quickly as you can through overpayments where possible and reducing the term on remortgage