OK...this is a bit confusing...if there were restaurants that specifically removed lobster, and other "pricey" items from their menus during the period of
free dining, then put those items back on their menus after free dining was over, then yes, it certainly looks like free dining was the cause. If those restaurants simply changed their menus, it could be just to reflect what the patrons want, and have absolutely nothing to do with free dining.

Restaurants change their menus occasionally -- even those
not at WDW
For lobster lovers, I went on the Great Lobster Hunt for you (even though, ugh, I hate the beasties!

I will gladly give you my share

):
None at AK, obviously.
At MGM, the only likely candidate is HBD -- no lobster on the menu (except lobster bisque), but the "priciest" item is Filet Mignon for 28.99.
In Epcot, Bistro de Paris has lobster but isn't on the DDP, so would be unaffected.
No lobster at Chef's de France, "priciest" menu item is beef tenderloin for 28.95.
Filet at Le Cellier 27.99, no lobster.
Coral Reef has lobster soup, but most expensive entree is NY Strip, 31.99.
Jiko -- Filet Mignon, $34.00.
Flying Fish -- lobster appetizer $18.00, veal chop $39.00 is the most expensive entree.
California Grill -- lobster appetizer $17.00, filet of beef $35.00.
Concourse Steakhouse -- lobster bisque $6.99, Filet Mignon $26.99.
Maya Grill -- lobster is in the Seafood Margarita $9.95, "priciest" entree Mixed Grill $29.99.
Shula's Steakhouse and bluezoo at the Dolphin both have several lobster dishes, but are not on the DDP -- can you use DDE card there? And they are
expensive
Citrico's -- no lobster, most expensive entree Filet Sicilian $36.00.
Narcoossee's -- Steamed Whole Lobster $54.00, Filet Mignon and Lobster Tail $52.
Artist Point -- no lobster, three menu items are $32.00, Salmon, Beef Tenderloin, or Sirloin Steak.
Yachtsman Steakhouse -- Lobster Bisque, $9.00. Ribeye and Porterhouse both $42.00.
Cap'n Jack's -- add a lobster tail to any entree for $12. Twin Lobster Tails $31.99.
Fulton's Crab House -- lotsa lobster (and costly, up to $49.95) but not on DDP. Can you use DDE here?
Is it that there are restaurants that
used to serve lobster, and no longer do -- at all? Which ones? Did
any of these restaurants remove lobster from their menus -- or the "priciest" entrees I've listed -- during the period of free dining last year...or the year before?