Steve,
It was not so much the arrogance of the Officers, but more a reflection of the then recent history.
Back when the Lee Metford was designed, the state of the art BritishRifle was a Martini Henry. This falling block action was a single shot rifle.
So the previous rifle which had helped maintain the Empire, was a single shot with no Magazine. The standard operating proceedure was that riflemen loaded and fired on command.
The jump to a 10 round magazine bolt action rifle enabled a change in the way a rifle company operated, but it took a period for this to be worked out.
Rather than seeing that they now had a 10 round rifle, they saw that they had a single shot rifle, with 10 rounds in the magazine.
So I would not argue it was because of arrogance, but more because they still had not worked out how to fully capitalise on this new technology.
But then again, many of the Officer Corps appears to have been selected by parentage/class rather than merit.
History does show that the upper classes were often very arrogant, ( and from a shallow gene pool)