The Parliament Act is only a distraction, and it doesn't have anything to do with the electoral system, or the composition of the House of Commons at all.
Your argument appears to be:
- We have an adversarial style of government, and that is a good thing.
- FPTP is necessary because only that system produces results conducive to that style. It apparently produces a strong opposition (in the Commons) which can knock the corners off proposed bills and make them better.
- PR would require a consensual style and this produces "wishy washy" bad law.
- The Fox Hunting Bill was an example of this wishy washy bad law.
But...
The Fox Hunting Bill didn't have any rough edges smoothed off by a strong opposition in the House of Commons. There was, of course, opposition to the Bill from the Conservative Party (and even from a few Labour members, I believe). However, the Bill was able to pass these stages fairly easily because the Labour Party had an enormous majority of MPs, and so any opposition was effectively fruitless. This big majority was a direct result of the FPTP voting system.
The Bill was rejected by the House of Lords, an unelected chamber where, in fact, there is not a strong majority of any particular party. Using the Parliament Act to override this is perhaps questionable, and may have been a wrong move on the part of the government. But in the context of a discussion about whether PR or FPTP produce a better style of politics in the House of Commons, it is basically irrelevant.
If anything, your example of the Fox Hunting Bill actually disproves your case: it is an example of a bad law that was allowed to pass in the Commons because of FPTP. Had there been a coalition or minority government, it may well have been the case that such a law would not have passed, as negotiation with other parties would have been necessary to gain a majority on the vote. The absence of a Labour majority in the House of Lords is probably why it didn't pass there.