We seem to go round this buoy on a fairly regular basis. Those advocating the need for additional equipment and/or manpower often present logical and informed argument (Party Animal for example). However, if the UK were to procure such items then there is a simple choice:
a. Allocate more money for Defence, or
b. Reduce/delete an alternative capability
The reality is Joe Public is not clamoring for more money to be spent on Defence. Indeed, if anything, his expectation seems to be for less. The politician class are very good at reading the pulse of the Nation, as (with a few notable exceptions in history) they tend to follow public opinion, rather than shape it.
So that leave us with option B. SDSR15 is likely to play out with intense debate over the merits of our existing and planned ORBAT, so perhaps it would be useful for those posting who believe we should have more of X, to explain why they also think we should have less of Y.