The most important thing for military equipment is reliability. Straight pull designs generally don't have the same initial extraction leverage as turn-bolt ones and they can get jammed with mud or grit more easily under field conditions. (Mind you, the Swiss M1931 has a pretty good reputation.)
Do some reading on the Ross Rifle in battle with the Canadian Expeditionary Force in World War One. It's not a pretty story. From the Official History of the Canadian Army in the First World War:
The Ross was a political purchase and became a political football. While it was an excellent sporting, target and sniper rifle, it was monumentally unsuited for use by line grunts in the mud of WW1 trenches. Troops began tossing theirs whenever they could get their hands on the more reliable Lee-Enfield and eventually Ottawa gave in and bought Lee-Enfields officially.
I like mine, but I wouldn't want to have to carry it into battle.
It was purchased because during the Boer War, Canada had difficulty getting sufficient supplies of small arms from the UK and it was realized that in time of war UK manufacturers would be fully occupied supplying "Imperial" forces. The British gun trade and the War Department refused to set up factories in Canada for reasons of profit. So, along came Sir Charles with his own capital and his own rifle; "perfect" the government thought, "problem solved for no cost to us", and in those days governments were very parsimonious!
If the British had licensed production of the Lee Enfield in Canada or otherwise assisted in starting production of the Lee Enfield here, you can bet that is what the government of the day would have gone with, since standardization of arms was understood and desired even then.
It's all about money folks: keeping "the colonies" as a market for your goods and a source of raw materials. Same situation as today as far as Canada is concerned.
The UK gun trade wanted to shut Ross down, and in the end he was. And then, when the company had become a Crown corporation, the War Department delayed sending the drawings and gauges for the Pattern 14 rifle as long as possible so that production couldn't start until the war was almost over and the contracts could be cancelled for "business" reasons.
"Just follow the money", as always.
The Ross wasn't much longer than the Gew98: the Germans seem to have managed fine with that in the trenches didn't they?
