FG's should be adjusted with Mash temps, not sure how racking to a secondary would stop it from continuing to ferment...or do you just not take another reading after you rack? cuz I bet it continues to go down..
+1. Most brewers are not going to stop the fermentation prematurely, that would lead to sweetness not maltiness, as well as acetydehyde and diacetyl in some cases and bottle bombs in others. We already have ways to get more body or more malt flavor without the negatives of prematurely ending fermentation. If you want more body, mash at a higher temperature. If you want more maltyness, use a 'maltier' malt (like english pale ale malt instead of 2-row, or munich/melanoidin/aromatic malt).
All that said, wine/mead makers do stop fermentation, but they've got a different product all together that I don't totally understand. Either way I don't think it really works in beer.