Reasons why people get upset over this...
1. The person asking for the share is often extremely rude about it.
2. It shows a complete lack of appreciation for game exploration.
3. Shows a lack of knowledge of basic game tools. (ie. quest log, lfg information provided...)
4. Shows laziness on persons part that is asking.
5. Questionable skills and here's why... If they can't do their part to pick up the quest, are they going to contribute in the quest. This may seem silly but it still runs through my mind, especially when the quest giver is at the entrance. In other words,"Great! Another piker."
The worst part is I am in a guild that goes out of their way to teach people game mechanics, basic strategies, and just about anything else they need or want to know. I am not an expert, but the entire guild together has an average experience in this game at 3 years. My experience so far has been that people who rudely ask for a share (not the forget kind, mind you) tend to be people that will not listen, does not contribute in any way, does not assist with any type of questing strategy for the party, and refuse to learn from ANYONE!