At SAS, they found some abnormalities within the system, such as stray gaskets sitting in actuators that should not have been in the entire system at all or corroded parts.
For example on the Aalborg incident, the cylinder that was to dampen the extension of the left main gear did not work to this effect, so the leg just slammed out and broke the downlock in the process. It then just dangled outside of the nacelle and would obviously not take any load during landing. IIRC, this was known and reacted to by the crews before touch down.
This was followed up by ADs mandating fleet wide gear inspections depending on hours and legs flown, and as far as I know, the problems SAS suffered from have never reared their head again. And for what itīs worth, I have flown the DH8 for a while now and never had nor heard of an issue with the landing gear in my company...
I would suggest that simply pointing to an inherent weakness of the DH8s landing gear as a possible cause for this incident would be too easy and inappropriate.