I like the current implementation whereby 1 novax can be strong (not always though - generally it's good on larger maps with lots of spread out mexes), while lots of novaxes are significantly weaker. Ultimately such an approach helps increase variety in games due to encouraging a mix of units instead of just spamming a single unit.
While it is still possible to spam novax, that doesn't mean it was the best decision - while there are some niche scenarios where multiple novaxes are better than novax+T3 arti, in most cases T3 arti is better (i.e. if you're trying to break a heavily defended location, or want to cause widespread damage to a poorly shielded base).
Since it's a satellite, it also seems aligned with the idea of the unit that it provides good vision and radar.
As to whether it's overpowered because it makes t3 spy planes redundant, the intel is just a nice bonus to the unit and is almost never worth building for it (Aeon's Eye of Rihanne provides far better intel for a much smaller cost yet seems to be rarely built). I also dont find the numbers given for the mass savings from a novax convincing - if you're building a large wave of spy planes you're often scouting most of the map with them in one wave. To use a novax to try and scout most of the map is a huge waste of resources. Where I find its scouting useful is if I'm already targeting vulnerable enemy targets (e.g. unshielded mexes and pgens), and there's a section my spy planes haven't managed to reach for a while where I'm worried the enemy could have a nasty surprise (nuke, t3 arti, etc.).
The main issues I have with Novax are more around how even if scouted early it's difficult to cost efficiently counter on certain maps (but this is more of a map variance point - on some maps it can be defended against for a fraction of the cost, i.e. it's sometimes a weak unit sometimes a strong unit, depending on the map and situation, which I don't see as a bad thing), and how it seems to easily counter fatboys (might be a skill issue on my part, but with the fatboys slow speed, low health, and high cost it feels like a novax can force the fatboy to stay on defence)