Lets see.

As we both probably agree, the nominal money supply does not matter. E.g. there is no functional difference between 1 million dollars in total supply and 1 billion. All prices are nominally higher in the latter case, but the relative distribution of wealth is the same. (In other words, rename "1000 dollars" into "1 shmollar" and you'll get the same prices in 1bln economy as in 1mln economy.)

Since all that matters is relative distribution, when anyone increases money supply, it matters to whom it will go. If your central bank prints new dollars and distributes them to everyone in proportion to their existing holdings, relative distribution does not change. Prices will rise, but wealth will not move.

If, however, the central bank prints new money and gives only to some people, they will have higher purchasing power comparing to anyone who did not get the new money. The money is being shifted towards those who are closer to central bank, so their economical decisions get more power. Example: today we both have $1 and compete equally for 1 apple. Tomorrow I get extra $1, so I can outbid you for 1 apple at a price $1,15 per apple. You didn't get the best apple and I still have $0,85 to outbid you elsewhere on the market. So my new money raises prices for both of us, but I have more of it, so I'm more frequently outbidding you and buying what you cannot buy anymore.

If this game is voluntary (e.g. if we voluntarily use gold as money and some people dig it from the ground on regular basis), I have no problem with it. If suddenly someone discovers an infinite gold mine and starts affecting everyone's wealth, I may choose to use something more stable as money. Or may stick to gold if its utility is still better than the price of inflation.

However, if the game is not voluntary, then we have a huge conflict of interests. If everyone in the country is OBLIGED (directly with legal tender laws and taxation in USD, and indirectly via various currency controls) to significant extent to store and transact money in centrally-controlled currency (e.g. USD), then those who control money supply get huge power. They can reallocate resources wherever they please in a nice hidden manner. And users of the money cannot invalidate the scheme by switching to other money because of the aforementioned laws. And laws (by definition) are legal threats against disobedience. So if you don't like that your wealth is being diluted towards certain persons (e.g. generals and soldiers in Iraq), the only way to really confront this is to avoid using USD. But it's not that easy because of tons of guns pointed at various levels at many different people in the whole economy. If you even try to do something money-related, you'll be attacked pretty quickly on "money laundering" and "helping terrorists" grounds. Just look at what problems Bitcoin exchanges face and how banks are self-censoring by preemptively shutting down exchanges' accounts to avoid regulatory intervention and losing their license.

See also how the gold was confiscated by the feds in 1933 to avoid repeating the myth that "we switched from gold voluntarily to superior USD": http://4.bp.blogspot.com/-6okepMAnHdc/TZrXaHL7ymI/AAAAAAAAAe...

PS. On the "long run": it never happens. It is a moving target, but never a destination. A lot of individuals during "short runs" define how the wealth is spent and where investment goes. If music-loving individuals print themselves some money, the whole economy will slightly shift towards their music preferences and you'll have more music halls, concerts and sound studios than if they didn't print that money or if people could blacklist that printed money, or switch to another money.