Bastien relies a good deal on Boon, particularly Boon's concept of 'epidemic counterfeiting'. While shortage provides the opportunity, Boon argues that profit is a primary motive throughout. As noted, Boon's focus is Britain but the island is not considered in isolation and much of the article is applicable generally. There are two versions of Boon's article. The first (1974) is cited by Bastien. The second (revised and expanded) is cited above but the publication date should read 1988 rather than 1980.
But the only opportunity a counterfeiter needs is the right conditions to profit from his/her enterprise. In this case opportunity was presented by the right combination of material cost vs face value, which is an equation that changed favorably for the counterfeiter every time an inflation induced coinage reform upped the face value, helped as well by reductions in coin size. Look at modern UK - no coinage shortage for sure, yet 1-in-30 pound coins in circulation are counterfeit.
King ("Roman Copies" Coin Finds and Coin Use in the Roman World) gives a more nuanced look at these unofficial copies, though she agrees "the primary motivation...was greed."
Let's consider the Britain of the 2010s versus the Britain of the 350s. Imitations of the FEL TEMP REPARATIO 'fallen horseman' type are frequently found struck over Constantinian issues of the preceding period. Others are found in much reduced module. Diameters of less than 10mm are not uncommon. Neither of these characteristics are observed among modern British counterfeits. While profit remains the immediate motive, other factors are clearly at play.
Bastien's first four waves of "epidemic" counterfeits are of normal sized coins, not minims (p.145), and in discussing these being found in hoards he is clearly referring to high quality counterfeits that both aimed to and often succeeded in passing as genuine. The later (fallen horseman, etc) minims are really a case apart. We don't even know what value these were accepted at (being of such small size). It seems highly doubtful they were accepted as official or full face value. Even there, I'd want to see proof of necessity being part of the opportunity. Normally during inflationary times money becomes more and more worthless, so small change would be the last thing to be needed. Whether using lower value demonetized coins, or fresh flans, the profit motive would have been the same. The only difference with modern fakes is that most coinage systems use different modules and metals for different coins, so overstrikes are out of the question. The UK pound is bimetallic for instance.