Now I shall wait as long as possible before using crafting as all my stuff will be worth much more later.
Welllll... Culture needs grow as you progress through the chapters. You'll need much more culture in Chapter 5 to support all your buildings/upgrades than you will for Chapter 2 for example. Take the build menu for culture bldgs for example. You'll unlock higher culture/square bldgs as you research the techs in the higher chapter. You don't have unlimited space, so you can't hold onto all the past culture bldgs. So (I'm an elf, ymmv) when I unlock the Whispering Trees, I sell off the Flying Boats and replace them with the trees. I get back a little coin and supplies because I spent them to build those menu bldgs.
Event bldgs sorta work the same way, giving higher culture for higher chapters, but they do not cost you to build them. They don't even tie up a builder for the 10 seconds it takes them to build.
Crafting seems to be an alternative way to get specific event bldgs instead of waiting weeks to see them offered in an event and then working to win them, so it makes sense to me that there is no compensation for the time/expense of crafting.
Also, don't forget the military bldgs. The one that gives troops gives more of them the higher the chapter. That doesn't mean I have no use for the smaller amounts in Ch4 where my squad sizes are smaller. So, I'll use crafting to upgrade those when the time comes. The expiring boosts bldgs are going to give the same % military boost to Ch 1 players as they do for Ch 12 players. Since that's their primary effect, I'm using them for 5 days in a tourney, they expire and get sold. I don't really care that a Ch4 one gave me 35 culture and a Ch 11 gives me 220 culture.
Still, marathon, not sprint like kayleegrrl said above. Not draining my spells/instants/summonings and going crazy with it, lol! I did go through some in the beginning as I wanted to replace last year's winter set orc vortexes with the orc nests allowing me to get rid of that set making more room for these event bldgs. But, I mainly trashed old event bldgs I had never placed that just sat in inventory until this crafting mechanism was released. There's speculation the restoration spell will launch early in the new year. That should work on event culture bldgs, but I'm not sure the effect on mixed reward event bldgs (like culture/pop, culture/troops, culture/goods, etc).
All that said, at some point I'm crafting a Frozen Unicorn for my Ch11 city. Not for culture or anything other than I don't have a unicorn that color, lol! Then the herd will have 7, so I'll need to pick another one to craft to make it an even number...I know, I'll start trying to get 2 of each color/type!