Charlequin, putting a highly playable rare cyle in a set actually decreases median pack value, by definition of the median and keeping the total average bounded by MSRP. It does increase the median box/bundle value a lot, which is the actual important metric. I know what you're trying to say, but I guess you're more talking about the median value over an average of a certain number of packs. Whether the same value is concentrated in the top 2% or in the top 15% doesn't influence the median if the total average remains the same.
I feel like M10 and Zen was the period when super expensive new cards started to become acceptable. After that (and maybe because of the mythic rarity), cards preordering $40+ started to become far more common even though they dropped a lot after. Jace was the craziest card we ever had though, doubt we'll see a $80 card in Standard soon.
Fetches won't be in standard anytime soon because I feel they feared those crazy 4C or 5C manabases too hard. But I hope they do them once again, but it's going to take awhile I guess. Putting them in MM hasn't decreased their value as much as I'd like.