If you like the idea of last-minute ("this weekend", "tomorrow", etc) personal trips, travel credit cards are a good way to enjoy that freedom and avoid paying through the nose.
To clarify: I think it's still worth it despite the new restrictions on Delta.
On UA and AA, you might find saver award availability, but close-in booking fees are charged for non-elites (award travel may still be a good deal even considering this fee). Delta doesn’t charge those fees, but they have implemented dynamic award faring, including advance purchase requirements, so last-minute award travel will tend to cost more miles just like how the cash fare tends to be higher too.
The thing that airlines need to be careful of when following Delta down this road of revenue-based earning, fare-based redemption is that their programs are turning into basic rebates. If you earn one mile/$ with your credit card spend, and can only redeem for $0.01/mile (a valuation DL seems to be striving to normalize award redemptions at), it makes little sense to spend on that card and earn effectively a 1% rebate, while there are other cards that offer 2% cash back on all purchases or others that have high category bonuses. I’m sure there are plenty of people who won’t bother to do even basic math, but this risks the future of loyalty programs (and even the entire airlines themselves) that are propped up on revenue from mileage sales to co-branded credit card partners.