I think blame rests primarily with the Republican side, because I think that a critical mass of congressional Democrats would have squawked and squirmed but would, in the end, have voted for a grand bargain—whereas Tea Partyized Republicans just would not. But let's not kid ourselves: what we're seeing here is a result of the systematic underrepresentation of moderates in both parties, because moderates are the constituency for a hostage trade: they would rather solve the problem than stay pure and score political points. If you want bold solutions, vote for the least radical candidate in your party's congressional primary next year.
I with agree with the blame part. Cutting $4 trillion from the budget is a win for Republicans, especially since defense probably won't be significantly cut. And that probably gets a few Democratic votes in the House and passes the Senate with a majority of Democrats voting for it. So it seems likely the reason a deal hasn't been reached is that Republicans don't want revenue increases.
The part I don't quite agree with is the notion that the reason we have this ridiculous negotiation going on because there aren't enough moderates in Congress or presumably in the White House. And that if we had more moderates we would get more bold solutions, or that bold solutions would be a good thing.
If we are looking at this from the point of view of the entire political spectrum I would agree that there aren't a lot of moderates in the GOP. Boehner kind of looks like a moderate when he deals with Obama but that is because we are comparing him to the rest of the GOP, which is pretty far out to the right these days. And it would be a good thing if at least some Republicans endorsed economic policies that were coherent with decent economic theory.
As it is though, I'd argue we get bold solutions as a result from the staunch anti-tax policies of the GOP, like for instance, cutting taxes and raising spending while not wanting to regulate anything (i.e. the Bush years). And they aren't solutions that help anyone aside from the very rich. So I think moderates in the GOP would help create economically sound and boring solutions that would actually help solve problems.
On the Democratic side I think more moderates would create more of the same policies we have seen during the past three years, which is to say fairly moderate policies. A bold policy would have been single payer as part of the ACA. Instead we got an individual mandate, which was a policy idea taken from Republicans. A bold policy would have been $1 trillion plus in stimulus, direct aid to states to fix their budgets, and the raising of inflation. Yet because of moderates like Obama and the blue dog Democrats in the Senate we got moderate policies that didn't have the desired outcome.
More moderate Democrats would just move the median policy more to the right and thus give more leverage to radical Republicans. That would probably create more bold policies, but also bad policies. More moderate Republicans would probably have already reached a deal on the debt ceiling that included spending cuts and revenue increases. Or they could have possibly reached the bold policy of simply raising the debt ceiling on its own like we have every other time it was needed. So in sum, I think bold is relative and wouldn't necessarily lead to better policies.