Republicans wanted to nominate him because four years of Clinton would have been better for their brand ahead of 2000.
I think if anything, by the second half of 1995 it was pretty clear Clinton would win due to Gingrich's extremism so the party had to put up some sacrificial lamb, and given Dole was 73 he could never run for President again so he accepted. I think in 1980 or in 1988 he would have made a strong candidate but by 1996 it was clear that his time had come and gone. I think the nomination would have gone to somebody else had Gingrich not killed the GOP's chances for '96.
And anyway even if the GOP could have won in 1996, they had a very thin pool of electable candidates that had the experience necessary at that point to run for President and who weren't already well past their prime; especially after HW announced after the 1994 midterms that he wasn't running. The Class of 1980 was too old and the Class of 1994 was too inexperienced at that point. Other than Dole the only other people I could realistically imagine being the GOP nominees were HW (assuming he changed his mind, but I don't think he would have), Colin Powell, James Baker and Jack Kemp. Except for Baker, I think they would have all been stronger candidates than Dole. My guess is the nomination would have been HW's had he wanted it again and probably Kemp's if HW stuck to his decision.