I'm not an expert but I'm pretty sure the pumpkins you carve are not the same pumpkins you eat. You can roast the seeds, sure, but the inside will probably taste like dirt
It can be. Lots of people do eat whats inside pumpkins that they carve. pies, curries, etc. I feel like in terms of waste is one of the much lesser wasteful things people are doing and it often makes good feed and compost