We are planning to eventually give you the ability to edit transactions (purchases, sales & farming actions) instead of voiding and re-entering them. The problem that we run into is that it is a lot more complicated for us to change a transaction since we are a full accounting package with both cash & accrual books. What this means is that we can't allow you to just change transactions. A good accounting package instead must make an entry to reverse the first entry and then record a new entry just as you want to see it. This is a feature that is designed to protect you by not allowing others to change your records (whether accidentally or on purpose) without leaving a trail of what they did. Since Quicken is not a full accounting package, they can allow you to change entries (but remember once you change something you have no record of what used to be there).
Again, we are planning a future version that will include these changes, but it probably won't be right away.