My opinion is the term as Horace used it was more than just enjoyment of the day, more like give up hope in the future and give all to the pleasures offered at the moment. I think this is more what the OP had in mind also, "...savour every moment with all that we have?" This is contradictory to prudence (best word I could think of for the moment). It is a difficult task to achieve merriment, much less adventure, by exhausting all that I have today if I have the nagging feeling of having nothing for tomorrow. I won't even start on all the fetters just living places on us.
Most of my pleasures and enjoyments are also ridiculously cheap, a good book, good conversation with good friends, or a day spent fly fishing and I will drop most everything to enjoy these gratifying things, but that's not what I imagine Horace had in mind.