Pete:

Long history of that; there were some minor complaints during Korea in which some European support was provided (but only by the British in any reasonable strength), many major screams from Europe about Viet Nam (far worse than the noise about Iraq...). France, a noted intervenor in former French Colonies complaining about Iraq causing much frothing about the French to include the abysmally stupid 'Freedom Fries.' That and Russia complaining about US meddling anywhere are some examples of the castigation bit. Western Europe in general for not handling the Bosnian and Kosovo operations. Note I said "some" criticism -- it's quite minor but present and waxes and wanes with the mood of the day...

Dayuhan:
A better measure of affordability would be the cost of these wars as a percentage of discretionary federal spending... along with, of course, a look at what's competing for slices of that pie.
Basically true in one sense but I broadly disagree as I strongly believe the Federal Government's overarching problem is that it is trying to do too many things that are none of its business and therefor fails to do a decent job of the things it should be doing. I also have hangups with the phrases 'entitlements,' 'non-discretionary' or 'mandatory' spending. Affordability is really dictated not by those things but by funds available and the priority accorded a particular issue. In essence, that 'discretionary' spending bit is a political sham -- all the programs, including Social Security and Medicare / Medicaid exist as whims of Congress. The entire Federal budget other than interest on the National Debt is actually discretionary.

However, in the interest of fairness, one can check this LINK and get a picture of all that. Note that about 25% of outlays are not Federal Business but Federal intrusions into State and Local business and are a mix of Federal expenditures (relatively small amounts) and grants and transfers to the States and Localities. Dumb way to do business but it gives the Federal government the ability to micromanage programs and people. Note also at the bottom of the page the amounts the Federal government disburses in the 'Mandatory' category on things also not its busness (IMO).

All that said, it is reality and the net cost of the wars over the past 10 years has averaged a little less than $120B per year. As 'discretionary spending averages about a third of the budget (average for the period 2.4T) or around 800B per year so the 'war cost' is about 15% of Discretionary Spending, 20% of DoD spending -- which is at it's historic level of approximately 20% of Federal outlays -- it's hovered there in most of our peacetime years since 1945. Here's another chart with a reasonably accurate 10 year breakdown. (LINK).

Any way you look at it, the costs of these wars in dollars has not been excessive as a fraction of expenditures.