For myself, I can understand the need for balance and the DM's right to make decisions about how he wants his game to be run.
On the other hand, from a player perspective, "nerfing" is usually not something to look forward to. In the player's mind, it sometimes feels as if they are being "punished" for coming up with an interesting or "cool new way" to handle a situation using the rules "as is". Sometimes, it is "unbalanced" for the particular campaign they are in, somtimes it is not.
In my opinion, I believe that a major part of what is considered "balanced" or "broken" lies in the playstyle/campaign of the players and DM. For example, the tumble rules "as is" in the PHB may be perfectly fine in one campaign, but for another, the DM may decide they are "broken" and may opt to use a variant rule such as the one in Arcana Unearthed.
My personal gripe is when DMs wish to "nerf" a rule, based not on an obvious game breaking mechanic, but based on their own "opinion" on how a particular rule/skill/spell should be handled regardless of "balance". For example, a DM wishing to change the damage of a particular weapon, not because it is actually unbalancing the campaign, but because the DM feels that based on the description and his perceptions of said weapon, it should be weaker. Hopefully this makes some sort of sense and you can get the general idea. Maybe somewhat can better articulate what I am trying to say?
Anyways, although I understand and respect a DMs right to be the final decision maker in a campaign, that doesn't necesarrily mean I have to agree or like it. I will go along with it, but don't expect me to say the DM is right.
