Not only do you get the capability/skillset TODAY, instead of incubating/hatching/growing it over a decade at likely far greater cost, but you get the additional benefit of now having someone with deep interpersonal connections(besides any inter service connections) that can also reaps some benefits.
It's almost embarrassing in a way......the other service invested jillions in their training and development.....you've simply vetted them to ensure they aren't "That guy" Mr Turdtastic...paid them to shift and give them a new uniform and a paycheque......I would half expect an invoice from the service they are poached from.
I don't like using sports analogies with the military, but if a successful team can recruit talent from another team to boost it's performance, AS WELL AS, develop it's own organic talent....it highly likely to be better than a team that JUST produces talent internally/organically...all other things being equal.
Personally, I'd far rather have a couple SNCO mentors with deep and broad experience from everywhere on the planet to learn from but be stuck carrying a Lee Enfield rifle and ancient kit than to have SNCOs with far less depth and breadth of experience while carrying a plasma rifle in the 40 watt range.
The Army and the other lesser services aren't sitting in an armory, sitting in a hanger, or sitting alongside a pier.....it walks in and out the gate every day.
On an unrelated note....check out that Thales Hawkei wagon.........that looks purdy.....almost like a Bushmaster rooted an uparmored HUMMVEE.....I wonder if they accept trade-ins using armored Pinzies?