It's a bit hard to tell it was a flop. It is a new category for BMW and certainly some of the discounts available might suggest sales were less than hoped. On the other hand, the US is likely the largest market for the R18 & unit sales increased there from 12,000 to 16,000 year over year or ~32%. Looking globally, unit sales climbed from 169,272 to 194,261. While the new RT was also released in 21, the R18 line was the other major release. Other models were carry overs from prior years, so it's not unreasonable to infer that much of the overall increase came from the R18 line especially since BMW's press release calls out the R18 as driving much of the increase of the boxer based models.
Now for some irony, Harley in 2021 had 194,252 units sold globally, about 9 fewer than BMW! Harley launched the Pan America in 2021 and many consider it a good launch, yet Harley's overall sales increased 7.8% from 2020, while BMW increased 14.8%. So was Harley more successful with the new Pan America than BMW with the R18, or was it the other way around?
U.S. sales may have grown from 12,000 to 18,000, but how many were R18s? I purchased mine in late 2021 and it was one of VERY few that had been sold in the entire Region. Even in the largest market of California I see dealers still have new left over R18 inventory. Anyway, I do hope the incentives helped with establishing some sustainable momentum as it is an incredible motorcycle, but they botched the first release IMO and now have to get their shit together making accessories available, etc.
As to Harley, I think they too dropped the ball on releasing the 1250 models with multiple delays and their line in general is bloated with mostly overlapping models and little that talks dirty to me. That said, their fit and finish, fueling, etc., as well as ease of maintenance and aftermarket support defines Top Shelf. Their business model has weak links too though from the bad paper and stimulus bail outs, revolving door CEOs, etc., etc. Indian has small numbers too and they gave a poke in Harley's ass more than BMW will with the R18, but all competition is good for riders regardless what they choose to buy. I do think BMW is chasing man buns and Orange County Chopper demographics (at least in their video ads), which is fine to chase conquest sales, but going by the people that post on the forums they at this point have more "traditional" purchasers be they long time BMW or other Brand cross shoppers that may have a focus BMW should not ignore nor take for granted.
As to the Pan American v. GS, if not for continually returning for shaft v. chain final drive I would go for the Harley or the very nicely updated KTM options. All the electronics are adding $$$$ to these bikes, but we're looking at almost $28,000 U.S.D. for a fully loaded GSA and $25,000.00 for the GS that is huge jump from not so long ago and the KTM S or R and Pan American are just shy of $20,000.00 and have been upgraded in fit, finish and even offer some goodies the BMW doesn't have. I would really have to think hard why I should buy another GS/A as that is serious money and will provide for a bunch of chain lube, tires, gas, servicing, etc., etc., etc.
Bottom line, there are so many great motorcycles being offered nowadays that major issues are almost nil and the rest are minor and easily addressed. It's a very good time to enjoy motorsports in general.