Some people(like me) do not like to play as vasari.Therefore giving one race huge advantages(like the egg) makes the game not nearly as fun.
So, rather than letting each race have their own huge advantage, you'd prefer that no race had any significant advantage over any other race in any area of the game? That sounds boring to me. Going that direction the Advent shouldn't have the tactical advantage of being able to upgrade tactical slots everywhere via tech and TEC not the advantage of being able to upgrade logistics slots everywhere with tech, and yet, their very different focuses and being consistently strong within their focus is what makes all three factions interesting to play.
This is very nicely continued in Entrenchment.
The Vasari gets a bad-arse mobile close combat Starbase with a very heavy focus on defensive abilities for its own use and the ability to use another core Vasari playstyle: the phase gate. It should be noted that this does not automatically make it easy to bring forces into somebody elses rear area, nor does it strictly speaking bring an ability to the Vasari that they did not already have - you need to get there with a migrator and finish building and upgrading a Starbase, and what you can accomplish when you have done that is exactly the same as you'd have done by flying a level 6 Marauder there instead of the migrator (apart from not needing to spend the time building and upgrading). Economically, the Starbase provides a colonists-in-space bonus for more credits, useful in all non-frontline systems. On the other hand, the starbase brings nothing to help a friendly fleet in the area - it is a combat juggernaut, everybody else can look out for themselves. Now, Entrenchment is not just about the Starbases but also the other defensive installations, and the extra abilities to their old defensive systems are rather meh: the hangar's get to immobilize strike craft and their phase missile launchers get to halt the hull/shield/antimatter regeneration of their targets - again, this is very much in line with the Vasari ideas, but most people would probably prefer something like the TEC upgrades - and that's fair enough.
Advent gets superior civilian starbases via higher allegiance (mimicking their Allure of the Unity tech and playing to what is already a strength of theirs - getting more resources out of each individual planet than anybody else), and can throw even more squadrons around in a gravity well than they are used to (one of the Advent focuses). Their Starbase might, in some cases, make sense to be used as far away from the expected entry point of hostile fleets as a sniper starbase - max squadrons and the ability to fling meteors at fleets as they approach may not be as effective at defending planets, but for survival, damagedealing, and making sure that no torpedo boats get into range of the starbase itself it probably cannot be beaten. On the other hand, their standard defenses get a considerable boost: Hangar platforms capable of shielding nearby buildings and beam weapon platforms gaining in strength and survivability when clumped together. This plays very well with their current ability to get up to ten more tactical points than anybody else and heavy focus on squadrons and shielding. One of those cases where placing the starbase behind normal defenses and hugging the planet would make sense - you tell me.
TEC Starbases give the TEC a genuinely new option: the ability to pump out frigates and cruisers on the spot even in neutral or hostile systems. This plays to the TEC strength - production. Likewise, their Starbase Docking Boom module is pure fleet support of the type that TEC lives on - more antimatter, more time to live for the heavily armoured fleets. While a Vasari Starbase might be individually more powerful than a TEC one, if you add an equivalent fleet to either of them the odds are likely to even out. The ability to blow itself up may not seem like much, but let us see how that plays out in practice. The extra abilities to TEC's old defenses are very substantial: Hangars now shoot down strike craft and Gauss Cannons are upgraded to be able to deal both with longer range threats and multiple close range threats.
For a breakdown of mines - somebody else must answer; I have very little experience with them yet.
Focusing solely on one aspect of the defensive changes, to whit, Vasari having moving Starbases, to the game in analysing future gameplay seems a wee bit narrowminded.
The one thing I guess we can all pretty much agree on is that it would be very, very, much appreciated if we could decommision Starbase upgrades selectively, thus allowing us over time to change the function of a Starbase without having to dismantle it entirely and rebuild from scratch. The Starbase that once defended your frontier could be retrofitted to an economic base once it is no longer relevant due to an advancing front; the Starbase that once was based on short range weaponry to have them ripped out and replaced with hangar bays.