I don't see anyone saying that they hate this card. Just because people have preferences doesn't mean that they hate the other options.
I didn't say they hate, and you're right, preferences don't automatically lead to downplaying other options. It is just matter of how much we let our preferences influence what we say to others.
For example my biases are that selling computer hardware is a hassle and my last two computers didn't iinclude upgrade paths. I will always make suggestions based on these ideas, my only missing pieces are the perogatives of others; which I don't need (but would help knowng).
Unless the OP wants to keep dual 450's for the life of his current or next system and change everything with the next one after, and since a third 450 cannot be installed, if he wants more performance before upgrading again, its probably better to get a single 460 now and a second later. But that would depend on perogative, preferences, current system configuration, etc.
The OP has a 9800GTX, a single GTS450 is > 50% faster using the same or less power, that is a gain by itself, but is it enough? The OP contemplated dual 450's, so that tells me not only could he afford a single 460, but the chances are pretty high he'll get used to the performance and want more sooner than later. From a marketing sense, SLi sells itself, few customers went back to single-GPU only to get another eventually. That's why 450 has the SLi option, nVidia can't survive if they restrict dual-GPU to only the more expensive products, there are more customers 460 on down than 465 on up. The idea is to sell more performance to lower markets so their next upgrades are better than the last.
If it were me and considering my bias about selling hardware, getting another 460 someday is easier than selling a pair of 450's for another pair of cards (say 650's given the timespread) as those 450's might not net as much cash back by then. A second 460 will be cheaper and adds value to the current single-460 system because its not like SLi = zero improvement.
I have a single 260, it more worth my money and time to get a second used 260 than trying to sell my 260 and get a single 460 or dual 450's because I don't already have enough funds to upgrade first and sell later; I'd have to sell the 260 first which isn't going to happen any time soon seeing how much demand and supply I'd have to fight against. If I started a post asking about upgrade options, a vast majority would suggest a 400 series upgrade. It could be coincedental they may all own 400-series cards, cannot stomach suggesting to buying older cards (even though two 260's are faster than one) and may not have trouble selling their hardware. They may disregard my budget, my hassles and even my OS limits. Like I said up top, their preferences influence their opinions quite a bit; they don't hate, just may not suggest.