Mileage refund after upgrade flight booking

Have been reading the thread recently regarding changes in mileages for reward and upgrade flights.
A few weeks ago I booked two flights, one UC reward and one up PE to UC upgrade. I was after return LHR-SFO flights but in the end had to settle for return leg from LAX due to availability.
Checking online today noticed 2 SFO reward flights had become available so rang up to change return leg. Had to pay reasonable change fee but was refunded 15000 miles for the reward flight!! y)
New mileage rates for upgrade now down to 25000 from 40000. Pleasantly surprised but hope it clarifies the mileage rate issues that have been discussed.

I am also surpised as if the price of something lowers after purchase you seldom get a refund for anything.

I am equally surprised why they have lowered many of the miles needed whilst at the same time making it easier to earn miles.

LHR-HKG is usually full anyway before they reduced the miles needed so not really sure what it is about.

How much was the cost? I've had a Econ to Upper upgrade booked since October and always value 10K points as 150 quid in value... Just wondering if worth the bother.

Change fee was £90. Would have changed anyway as wanted the different route but surprised to get the miles back.

How much was the cost? I've had a Econ to Upper upgrade booked since October and always value 10K points as 150 quid in value... Just wondering if worth the bother.

I understand where you got that figure from (being the purchase price) but they are worth way more than that.
10k gets you from Y to PE (which would usually cost a lot more than 150) but more importantly 20k gets you from PE to UC ...actually I am wrong now they changed the reward miles ... 15k gts you from PE into UC. Now that has to be worth way more than the GBP225 value you put on them !!

What I dont understand is that you can earn more miles than you redeem now on a trip. Take LHR-HKG for example: in PE (S) you earn 6000, plus 3,000 PE bonus plus 6,000 (if you are Gold) = 15,000 plus if you used the VS card to buy the ticket maybe another 3,000 (about GBP750 each way) - earning a total of 18,000 then you can use 15,000 to go from PE to UC and you still earnt 3,000 more than you spent.

As a customer I like this a lot. As a business man I think it is a bit daft !

I am also surpised as if the price of something lowers after purchase you seldom get a refund for anything.

Slightly O/T - and, btw, y) on the mileage refund - when I had to change a Virgin America flight in 2010 the total cost was the change fee less a adjustment to reflect the fact that price of the new flight was less than the price of the original.