Midweek magic events have been getting worse and worse recently, especially with regards to events that are denied being "all-access." Khans of Tarkir constructed was the latest, most glaring example. Instead of giving people a fun introduction to a more niche release and expanding player interest, you lock "free" weekly rewards behind a pseudo-paywall (money or wildcards spent on a card pool not legal in standard and with minimal viability in its legal formats) and give tons of people a bad impression.

Absolutely! Like MULTIPLAYER Historic Brawl please!

Evergreen formats should be all-access if anything.
Also duplicate protection for the rewards would be a great thing...

And make them all access. It's painfully clear that they are designed to drain wildcards instead of rewarding them

One of MTGs many strengths is the variety of formats that are available. For the purposes of a smooth playing experience for players I recognise it is not feasible for all such formats to be available all the time on MTG Arena, due to play queue times and other factors.

However, it is then extremely disappointing when mid week magic takes the form of evergreen formats such as Standard, Alchemy, Historic, Explorer , Brawl etc that are available all the time.

More unique formats such as Pauper, Artisan, Phantom Draft, Singleton, and a whole host of other creative formats should be the only formats chosen for Mid Week magic. Such formats provide a respite from what can otherwise become repetitive formats that are available whenever a player wants.