Why do the contribution page amount labels now appear before the amounts?
I can't find the exact issue or commit at the moment, but these changes were made to standardise the order the of the label and the price. Depending on the type of field used, the price and label were sometimes in a different order.

For example, in 4.4:



And in 4.6:



As a sidenote, I think we decided on the order 'Label - Price' because you would normally look at what you wanted to buy, and then how much it is. That made the most sense I think, when choosing ticket options for an event for example.