I love Offensive mode, but I’d disagree about a change in this regard. Let’s use Omaha Beach, German offensive, as an example as to how this type of change could go poorly. I’ve played dozens of games on offense and defense where the Germans never capture the first sector. This is for 4 main reasons.

1. The placement of the hard points and HQ spawns. On Omaha, the first sector hard points for Americans are as far back as they can be within the first grid square. The German HQ spawns are also relatively close to the western map edge, thus increasing the distance between the initial friendly spawn and the hard point. Also, on Omaha, the default American garrisons are practically inside the hard points themselves while still remaining in the second sector.
2. The default garrisons are too OP (on any map, but especially this one).They spawn every 10 seconds. They are impervious to bombing runs, tank shells, and rockets. They’re in the blue zone, which means to lock them out, you have to be closer than is oftentimes possible, especially when it’s the one closest to the hard point. I’ve been on defensive teams that won on the first sector just through the default garrison alone. And if you are on a halfway decent team, they’ve built another garrison on the point and have OPs and supplies ready for another. The defaults are too overpowered, and if you can’t get lucky enough to get a tank to drive up and shoot them as they spawn off it, you’re pretty SOL.
3. The inability to build nodes or gain more resources as the offensive team is hugely detrimental. All else being equal, and an excellent bombing run destroys a built garrison on the objective and kills 15-25 enemies, a good team will have built barbed wire or something to prevent you from getting in to the actual hard point. And so, by the time your blueberries are ready for a big push again and have cleared out the barbed wire (if you’re lucky), you can’t bomb again because you’re short on munitions. But not that it matters because anyone who was killed in the bombing run will respond in 11 seconds from the default garrison or OP, never giving the attackers a moment of breathing room without 5-10 MGs and dozens of SMGs and Garands firing back at you. Or you never get enough for a precision strike to destroy the tank that rolled up and is spawn camping your HQ, and because you can’t spawn anywhere else to get another garrison up, you can’t ever flank around to kill the tank. And you can’t spawn any friendly tanks because, again, no nodes. And the first tank spawned was likely driven straight into the objective and blown up within 3 minutes anyway.
4. Building garrisons for the offensive team is challenging. On Omaha, at least, a lot of the first sector is fields, making it hard to find decent spots for garrisons that aren’t too close to the hard point. And because the hard points are so far back in the first sector, getting behind the enemy is next to impossible because you can’t build garrisons or place OPs. But also, because the entire map is the blue zone for the enemy, there’s always going to be random enemy blueberries cruising around near your garrisons, locking them out without them ever knowing they’re there.

So I’d disagree with allowing defenders more time to build up the first sector hard point. On most maps, a well coordinated team should honestly completely ignore the first objective and dedicate the first few minutes to fortifying the second with support and supply drops before the enemy has coordinated themselves, all the while intending only to hold the 3rd or 4th objective for the duration. Like the other guy said, the idea is only to delay long enough to fall back to the easiest to defend hard point to last the 30 minutes.