Why do questions only have the option for an upvote? What if I want to vote against a particular issue?

We expose different features on desktop than on mobile. While we try and keep the two consistent, sometimes it's hard with the limited space mobile devices provide. Therefore we opt to emphasize the things most users care most about and voting is the most common form of engagement for most members.

Be careful with downvoting. Sometimes the poster is putting out information not supporting it. You would be down voting the poster not the subject matter.

Ahhhh! Finally found an answer. Found this on a Rally Point support page.

How do I vote down?
Members must have a minimum of 15,000 points in order to down vote. This is to prevent people ("trolls") who are not active members of the community from abusing this feature. Click on the thumbs down image below the poster's picture. You can undo your vote by clicking on the same vote button. You can also change your vote to an up vote by clicking on the thumbs up button. You only receive influence points on your first vote for any post, regardless of how many times you undo and redo your votes.