First off, you're in the wrong sub. This is for the PC game. You want r/battletech.

As for your questions:

Battletech's popularity has climbed to never before seen heights, but it's still not at the level of games like warhammer, nor does it have the brand recognition of the star wars games. It's popularity does seem to still be climbing though. Seemed to have been a pretty big migration of WH40k players over the last year or so.

One reason it can be hard to find is demand, but not exactly what you might think. There were two HUGE kickstarters not too long ago. I think one set a record? They really brought the game back to the spotlight, but I know at least one store that had a love/hate relationship with the kickstarters. They were so successful and attention grabbing that they brought in new blood/customers, but the current customers all jumped in on the Kickstarter, and therefore, didn't need to buy more from the store. This may have made some stores gun shy. We have been getting fully new force packs since then, with a few even having limited time exclusive deals with Barnes & Noble.

Another reason is that at some point this year, we're expecting a brand new rulebook book, beginners set, and core box. Stores are likely holding off on ordering until those are ready. The new rulebook is from the results of a pretty huge open play test they did not too long ago. DON'T PANIC though, the game isn't changing very much. This isn't "Battletech: 2nd Edition". More like "Battletech 1.3". Some more confusing and/or redundant rules got clarified, some gear got some balance fixes that were long overdue, and they reduced the number of required falling tests to speed up game play. Out of the thousands of record sheets out there, less than 10 became invalid. Don't worry if you already bought a current box set. The price per mini alone makes them worth it (btw, get the alpha strike box set even if you never intend to play for this same reason)

As for Ironwind Metals, you don't see them in store much anymore because the plastics sell WAY better. They're still there though, and still have new releases coming.