Nice! That's a lot of accessories you've got there, it's definitely a work bike and not a recreation bike.
You don't need a cargo bike (those are expensive), consider a kid's bike trailer. They typically carry around 100lbs (45kgs?), which is plenty for larger trips (I've done some Costco runs w/ my bike trailer).
Looks like Thule services Malaysia, and I would be surprised if they're the only one. Find one for two kids, they'll have higher weight limits and be big enough for larger runs.
I use one from Trek, and I've carried:
car batteries
sacks of rice (like 20 kg)
bulk toilet paper
my kid's bike (SO picked them up w/ car, and I dropped by in the bike to get their bike)
It's nothing special, just a kid trailer and some creativity.
You don't need a cargo bike (those are expensive), consider a kid's bike trailer. They typically carry around 100lbs (45kgs?), which is plenty for larger trips (I've done some Costco runs w/ my bike trailer).
My errand getter is a steel 90s MTB. Front and rear racks + a few trailer options. I've been easily able to haul over 120lbs.
My favourite trailer, and one that I could recommend to pretty much anyone, is the burley travoy. So many benefits with the only con being it's price (especially with the extra accessories). Well, well worth it, IMO.
Yeah, if you're regularly doing heavy loads, getting a purpose-built trailer is a good idea. But if you're just getting groceries, you can probably get a kids trailer used for <$100.
Eh, I think the seat actually helps keep things organized. I put heavy, boxy things on the seat, lighter, bulky things in front of the seat, and bags and whatnot behind the seat. Mine looks something like this, and has the coverings and everything so things stay dry.
But I don't use it for carrying cargo every day, it's more of an occasional thing. If we go together, we take the car, otherwise I'll try to take the bike so I get some exercise at the same time. If I did it more regularly, I'd probably get a proper trailer with a higher weight limit. But my city isn't really designed for cargo bikes (bike paths/lanes aren't near shopping areas, few proper bike racks, etc), so even if I had one, I probably wouldn't use it enough to justify it. But the kid's bike trailer is perfect because I live right next to a nice bike path that goes to a small fishing pond, so I'll take the kids with quite often. But even when the youngest outgrows it, I'll probably keep the trailer for hauling stuff.
Oh yeah, there is no right or wrong here. If it suits your needs, then it's a perfect trailer! I use mine for the grandkids, and because I have a regular cargo trailer and a Burley Travoy, my needs are met for medium/largo cargo requirements without having to use the kid's trailer.
But, I can see it being super useful and very cost-effective if you have kids, since you can use it with or without the kids.