Hour-long games are bad for the competitive scene, I don't think there's even an argument to be made otherwise. It puts tremendous stress on the casters as well as the players in the game, makes scheduling impractical, and stretches the patience of the viewers. While a best of three format may exacerbate this to some extent, this is not a problem unique to the Rumble and has the potential to happen in every event you will play in.
That being said, the responsibility of the teams who participate in the event is to win. It is not their responsibility to manage game length or optimize entertainment value for spectators. Those responsibilities fall onto Muse (to improve the game's balance), and myself (to organize events which properly function despite flaws in the game's balance). If a best of three set is three hours long, the event is not functioning properly and the rule-set needs to be adjusted.
It is however important to adjust the rules in a way that doesn't upset the balance of the event, in the same way it's important for the developer to maintain the balance of the mechanics themselves. Long-range conservative play should be just as viable as close-range aggressive play. The problem is not that teams are sniping. The problem is that those games are extending the length of the event too much.
The first change I'm going to make is to remove Canyon Ambush from the map pool. Canyon has historically been one of the problem maps in terms of game length, and with the recent additional cloud cover, even games between two aggressive teams can take upwards of 30 minutes as they circle around the map unable to engage. This will also remove the possibility of the "perfect storm" scenario we had last weekend of two sniping teams facing off with both Canyon and Fjords in their set.
In regards to additional rules regarding game length, it's in consideration. As I said, it is important to maintain the balance and limit the influence on teams choosing particular styles of play. Speaking on time limits, a simple "who's ahead" check bestows a large advantage to the team who wins the first engagement, and favours ships with more speed/maneuverability who would be able to evade for the rest of the game. This is one of the reasons a "fencing-style" rule granting priority wouldn't work either.