Solid rocket boosters provide more thrust per lb and don't have the refrigeration requirements that liquid fuel has. When designing the space shuttle they needed to get the payload higher for Pentagon for satellite deployment so they opted for solid rocket boosters that allowed the higher payloads. Several un-manned rockets that launch satellites use strap-on solid boosters for exactly this purpose.
Is that still true to this day? Why do solid fuels give more thrust per lb? Thanks for satisfying my nerdy curiosity btw.