What happened is that Spectre was the first instance of a new class of vulnerabilities, one which hadn't been considered previously. Side-channel attacks were already well known, but nobody seemed to have considered side channels from speculative execution before (it's hard to overstate how bizarre these vulnerabilities look like, from a software point of view: they're leaking information from a code path which has not been executed, could not execute, and in some cases doesn't even exist; that is, when looking only at the software, the leak appears to come from a parallel universe where an impossible code path actually executed).

Since this vulnerability class was previously unknown, hardware didn't have much protection against it, except by accident (or as a side effect of more conservative design). Being in hardware, they are difficult or impossible to workaround in software. And they were found in common hardware most people have. This all lead to them being widely reported by the tech press.