Ok, got it, 'Dad'.
Actually, one good technical reason to get as large a SSD as possible is due to the SSD's built in wear-leveling algorithims, having a SSD twice as big as a person (or organization's) largest projected storage generally speaking increases is lifespan.
Another is the general rule that larger SSDs are more recent technology, and therefore potentially have better built in algos for wear-leveling, and better (?) technology for the onboard controller. This isn't a hard and fast rule, however, and in your case you are getting what you get from Dell.
However, there is no one, pat answer for any individual - it depends on their use profile.
It is correct that M$ continues to cram more and more sh**, er, 'stuff' on to your storage medium, whether you want it or not, so that's a given.
Then indeed more is better.
Do you want to download lot's of movies? Do you keep them after watching? If not, then there's not as large an impact on space. Got the technical skill (copy -n- paste) and an external hard drive? Then you don't need as much local storage...
Movies are a relatively static storage issue, but if you have a lot of files which are updated
often, they begin to impact storage due to the wear-leveling algorithm in addition to their actual size. Probably safe to assume your needs may be more oriented to storing movies and pics vs. Oracle Databases, though...
I'm getting by fine with a 240gb SSD, plenty-o storage for my needs, but I've known folks that had network attached arrays of many terabytes, and weren't satisfied. It helps that I don't suffer the M$ 100gb 'hit', though.
One possible downside to larger and larger storage is the potential for a catastrophic failure of the device to cost you your records, your memories (pics and movies), etc., if it's a single point of failure.
As others have indicated on this thread and in many others, it's an excellent idea to have a backup plan and stick to it.
Perhaps a good non-technical reason to get as large a SSD as is affordable is the potential for economic and international commerce issues (price increases/lack of availability) in the future. Better to have and not need, than to need and not have... I've got a couple spares for this very reason. Only you can weigh the cost vs. benefits of this issue.
Regarding RAM, the general rule is to absolutely get what you can afford, and hopefully get a machine that is able to double that amount in the future as well. There is one very good reason for this: M$.
Good luck getting your gear, hunybee.