For one thing, it wasn't gratuitous. As you yourself already said, it was part of executions, which were undertaken as retribution for crimes.

On why people went to witness that, I'll have to say, as I always do with these kinds of questions, that anything we can elucidate is quite speculative, due to the nature of the matter. This is due to the fact that sociological analyses were not a common feature of pre-modern chroniclers, and even if it was, their own involvment in the mentality that allowed such activities would probably prevent them from assessing the matter in a strict form.

All of that being said, I speculate that it wasn't much a matter of enjoyment as it was of curiosity, and some times a decision influenced by anger. But even then, you have to take into account that many film depictions of this sort of behaviour, as well as pop history accounts of it, are sensationalized and exaggerated to appeal to a modern audience: "Look at what those medieval savages did! Thank God we are more civilized now and know better!"

hi! not sure how 'used to be' this sort of thing is, given modern-era examples such as lynchings and stonings. In any case, there's lots of room for more information here, but you may be interested in these earlier related posts, which focus particularly on your question about public attitudes

• Why did we used to be so fine with such brutal and public executions?

• During medieval times public torture and execution was commonplace, how did this effect the general population, did they become desensitized to gruesome death?

• What is this wheel on a pole with corpse that I see occasionally in medieval/renaissance art?

• How were executioners viewed by society in late medieval and early modern Europe?

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