... and why NOT? It makes sense for two understandable reasons that immediately spring to mind:
1. It provides the person from the other country - moreover, a completely different culture - with an ideal opportunity to sample the UK lifestyle ... not least, the infamous British Climate which, as we all know full well, is far from being amenable to everyone's tastes
AND
2. Pricewise, Visitor Visas work out at approximately one tenth of the cost of those required for Settlement purposes