Yes, this is your standard 'overthinking-stargate' post.
But given that the main rival to Jaffa and Goa'uld forces would traditionally be other Jaffa and Goa'uld, the primary (or secondary, second to policing civilians) threat would come from air assault and assorting air-support, given that Ha'tak could land, or bring gliders or both, and Al'kesh could show up independently of Ha'taks and gliders, you'd think that Jaffa would have ample air defenses. But as far as we've seen in the show, they don't.
What would complete the setting in that regard? Should they have had some sort of MANPADs? The ring-threading round gliders seem like the obvious choice, but they do not apparently make them as they once did, for some reason.
True, but the staff-cannon-things don't seem like a great alternative, given that they're usually fired from breast-hip height and seem to lack optics. And even if they did have optics, you'd think gliders and especially Al'kesh would already have engaged you.
Staff weapons against gliders, sure, but that just touches more on the cinema-cool element, where advanced aerospace-fighters are taken down by weapons that shouldn't hold a candle to that sort of platform. Another example is Shepard shooting down a wraith dart with an M249 (which he was carrying for whatever reason).
Stingers and AT-4's I can understand, but I feel like more realistically they'd be on the far edge of what could defend against gliders and darts.
I would assume that any air defence would be neutralized during the initial planetary bombardment after the attacking snake has dealt with any space based defence group.
The other option is anything cargo ship or higher have shields making ground based defence pointless.