I agree - myself I transfer everything into flight-miles on my 3 airline-accounts with UA, LH and SR - I concentrate and head for the airline miles with any program (Marriott, Hilton, Starwoods, Interconti, Holiday Inns, Diners, SR-Eurocard/Mastercard, VISA, Hertz, AVIS).

I am aware, that I miss some exceptional hotel/vacation deals/possibilities - but that way I always have a high enough balance of flightmiles to maximise their flight-value, either as:

* upgrades for me or my family;
* high-prized "last"minute inner-european flights for me or my family, that would credit anyway just a few miles if paid;
* luxury gifts to family members (transatlantic-award-tickets in Firstclass on three class aircrafts);
* airline-auction-participation for "out of the normal - once in a lifetime-events".

I pay directly (vacation 100%) or indirectly (business = 33%) out of my own pocket for all my travels & hotel-stays (on business or privat, most times a combination of both - ... at least taxwise ...).