In addition to kansface's point, I'd observe it's a
very recent addition. We made it a long way without it.
There's a quote referenced so often it has become a cliche: "Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away." by Antoine de Saint-Exupery. I think it's sometimes over-applied, but in the case of crypto software, it really fits. In a sense, the heartbeat code got unlucky and hit the mega-anti-jackpot, disproportional to its "actual" risk... but there was risk in adding it, and even before we know the outcome it would have, somebody really should have been asking hard questions about whether the reward justified the risk. I imagine there's a lot of other bits of the code where the risk/reward tradeoff suggests removal. You can look at much of what has already been trashed from that point of view. For instance, if you have no real need to support a particular defunct architecture, why carry around its code? It has no benefit, but non-zero risk; toast it.