For most cyclists, non-heat-moldable shoes work perfectly well. The majority of cycling shoes use standard construction where the fit is determined by the shoe's "last"—the foot-shaped mold the shoe is built around. Brands offer different lasts and width options to accommodate various foot shapes, so many riders find a comfortable fit without needing any customization.
If you have fairly typical feet and can find a shoe that feels good off the shelf, there's no real benefit to paying extra for heat moldability. Non-moldable shoes also tend to be simpler to buy and wear right away, with no special process required.
That said, if you have hard-to-fit feet—such as very wide forefeet, narrow heels, or bunions—heat-moldable options from brands like Bont or Lake can fine-tune the shape around your foot. Even with non-moldable shoes, you can still improve comfort with aftermarket insoles or by choosing models available in multiple widths.