It's a systemic flaw. You used to be able to memorise and cast spells like Charm Person or detect thoughts to assist in roleplaying encounters without taking 10 minutes plus and performing a ritual. In fact, Charm Person or Detect Thoughts could be very subtle spells, yet they don't exist in 4E in a form useable for non-combat encounters or in a subtle way.
I strongly disagree with the phrase "systematic flaw". It seems to imply that it's an objective fact rather than a matter of taste, or that it was oversight or lack of planning. It may not be your taste, but these were clearly intentional design decisions with specific reasons behind them.
You may think Charm Person and Detect Thoughts assist roleplaying, however others (including WotC) feels that these tie the hands of the DM and completely break stories, invalidates encounters, and can solve a mystery with no more effort than casting one of many plot-breaking spells. Since these types of spells do completely break many social encounters, I personally feel that they *hurt* roleplaying, not help it.
Plus it often leads to ridiculous arm races between players and DMs. Players memorize their list of broken spells, and DMs are forced to either let the players breeze his storylines with no real work, or he has to make his NPCs setup magical defenses against things, and this can repeat.
There are alot of spells like that in the new edition. For example, polymorph-based infiltration is not real possible in 4E as far as I could tell from the base rules.
I'm not sure why you'd think this. There are definitely polymorph, shape change, and disguise effects in 4E that most certainly could make this possible. Though, I suppose the Polymorph keyword didn't really appear in the first year of books.
The quick teleport in and knock open the door rescue mission is not going to be the same in 4E. You won't be casting teleport in combat any longer or knock.
Not as a party, but several classes (and races) have usable teleport powers in combat.
As for Knock, I think again this is an intentional feature. They want Wizards (or other ritual casters) to be able to use Knock as an option in case you don't have someone with Thieving skill, but in a way that doesn't invalidate the skill. I think it's a reasonable compromise. If you have to get a door open during combat, there's still the option to bash it in.
I've also seen attempting to open a magically locked door become part of a skill challenge in combat. While some members had to fend off the monsters, others could use skills such as Thievery, Arcana, or brute force to slowly remove the defenses of a door (or gate, wall, portal, etc) while in combat.
So no, it isn't just a play style issue. It's inherent in the system, which is more limited than previous editions of D&D primarily because the magic system is far more limited.
So now you hack your way in and hack your way out of just about everything. Though some DMs do creatively use skill challenges to resolve encounters. Skills challenges were a nice addition to the game, though at times all that rolling is pretty boring and lessens immersion.
You certainly more limited in a lot of plot, story, and encounter breaking powers.
Also, many spells that acted as a replacement for skills of previous editions have been toned down, removed, or turned into slower casting rituals in order to make skills or the classes that tend to have those skills more useful instead of being invalidated by casters.
They've tried to make skills more useful. A lot of people dislike how many skills were combined so that a smaller set of skills are present, and feel that actually reduced the impact of skills, but if you think about it that's exactly the opposite of what it does.
Decreasing the number of skills, making skills more broad, and making sure every class has a few skills to pick has the effect of greatly increasing the chances of someone in a party having a needed skill and makes it less likely that even your Fighter can often contribute when skills can be useful, rather than just slinking to the back of the party and wondering when the next combat will happen.
You see, many of these things that you dislike and see as flaws, some of us think are things that are healthy for gameplay. It's all about what style of game you want to play. For me, I prefer the 4E style.