I had no problem with the amount of Borg encounters in Voyager. If anything, I was anticipating it quite highly once Caretaker aired, since I remember the Borg were referenced in TNG as coming from the Delta Quadrant.
Actually, the very first reference to the Borg being from the Delta Quadrant was in
Star Trek: First Contact - which aired during Voyager's third season, between
Warlord and
The Q and the Grey.
Before that we had only seen the Borg seven times (
Q Who, The Best of Both Worlds I and II, I Borg, Descent I and II, and
Emissary).
In
Q Who we only find out that the Borg are in system J-25 and that Guinan is familiar with the system. There's no reference to the Delta Quadrant (since the whole concept of dividing the galaxy into four quadrants wasn't introduced until the next season of TNG.) In fact, J-25 was only 7,000 light-years from Federation space.
In
The Best of Both Worlds, I Borg, Descent, and
Emissary, there is no reference at all to where the Borg come from.
At the time Voyager premiered, I seem to remember hearing that Voyager might encounter the Borg at some point since the Borg were from the Delta Quadrant. However, I have absolutely no idea where this information came from. I also think that the Delta Quadrant in
First Contact, which is a simple throwaway line spoken by Crusher, was inserted to prepare the way for the Borg's introduction on Voyager, which would happen only a few months later.