I'd also add that it's probably entirely likely that Foma had secured a specific amount of the base (projected to last 10 years?) possibly in one batch - & they've obviously had other non gloss or matte stocks of varying degrees of lustre and texture - 113, 115, 133 etc. Problem is that there's an MOQ for manufacturing substrate probably considerably bigger than their minimum coating length.
Personally, I'd like to see them do something like Ilford's ART300 - Arches Hot Press watercolour paper would be nice - or a custom paper from St Cuthbert's Mill (aka Somerset) - and they are likely to have far smaller minimum orders than Schoeller (for example). From an archival standpoint, a pure linen base would be amazing, but the resultant paper would likely be astronomically expensive.