Just would like to add that there is a good reason for this policy.

Airlines have saved millions of Dollars by lowering service-levels for normal customers and reserve those benefits to their elite levels.

What nearly noone remembers is that at the start of Lufthansa Miles and More and when I learnt to know how BA Executive Club worked also the basic levels provided a seat reservation in shorthaul economy !

Afterwards (mainly in the 1997-2000 years) those basis service levels were continousely reduced so that they needed the differentiation between colour/tier miles and points and reedemable miles/points.

Also those customer loyalty programmes are a large cash-generator for them due to the fact that they sell the reedemable points/miles to other companies (e. g. hotel chains).

And not to disturb the ongoing segmentation, differentiation and as some would say discrimination of customers they will not offer colour points for any transferred values.