Yes & yes.
The plastic frames are provided by one of S&W's long time vendors. They just have to make the barrels & slides, and assemble the other various parts received from vendors.
They have to make the 3rd gen frames (approx 30 minutes on a CNC machine, per frame) as well as the slides & barrels. They also do some of the final machining & finishing in-house for other parts after they're received from vendors (like the manual safeties, slides stops, etc). Then, the 3rd gen's require some knowledge, experience and time for hand-checking & fitting the sear release levers and extractors.
Which do you think ultimately requires more time & money invested by the company? Which can provide the price point being demanded by the bulk of LE agency & private person buyers in today's market?
Sig has seemingly followed a similar path as the S&W of some years ago by adopting a gun-of-the-month philosophy. You really think they'd still be selling as many guns if all they made were a small number of classic models? Look at the pricing.
Look at the newer plastic models Sig has been working to to get up and running. Don't be surprised if they eventually get the P250 up and running and able to replace their metal-frame lineup for LE/Gov sales at some point.
Look at the effort Beretta has been making in introducing plastic pistols. The online "pistol" section is illustrated with one of their plastic guns. Their compact, subcompact & pocket categories are strongly slanted to newer plastic guns. Their "full-size" is an interesting thing to consider, though, since the pricing for the plastic & metal guns isn't really that far apart. Weird.
Like other folks, I've wondered how much longer they'll continue US production and sales of their 92/96/M9/90-TWO guns if the US military decides to shift procurement. It's not exactly common to see a lot of new Beretta metal guns in cop holsters, although you used to be able to see existing agency customers going from 9 to .40 at one time.
I've asked here before when this subject has come up, and I'll ask it again. How many of us are going to rush out to their local gunstore and put deposits on orders for new TSW's which will probably cost upwards of $1,000 - $1,200 per copy? I'd barely be willing to pay that for a PC or an 1911E series. (To be fair, though, in my case that's because of too many years of being spoiled by being able to buy discounted guns as an armorer.

)
Even if we were, it's not like it would be even a moderately profitable enterprise for the company. Not when they're using their production capability at their Houlton plant to make all the 1911's, .22's, PPK's and handcuffs they can churn out.
Each new 3rd gen they'd make would take a CNC machine away from making another model which has already proven that it can sell for a profitable price point.
I keep hearing that S&W would really like to see the 3rd gen's go away, even for LE sales for existing agency customers, within the next 10-15 years. The current market simply supports (and demands) the other metal-framed guns they're making at that plant.
Now, if one of the major distributors were to pony up the money for a special run of 20-25K new TSW's? Sure, they could get them, and probably for a decent discount (compared to only ordering a thousand guns). Might take some time, though. Then, they have to be able to sell them for enough to make a good profit on their investment ... as they aren't exactly operating a charity organization, right?
When I was seeing special Demo pricing on TSW's used for T&E for $600-$700/each I thought that was a lot ... and it
was more than it used to be ... but it was actually pretty decent compared to how high the prices had been climbing for MSRP and actual sales toward the end of the commercial production.
I do think it's somewhat sad to see S&W being foreced into the position of watching Sig being the one to carry the flag that S&W essentially started in this country, meaning meal-framed TDA guns, and then the SRT (which we were told in a Sig armorer class had been designed to try and help them compete against a S&W LE bid).
But, the market forces are something that are going to continue to have the strongest influence in gun sales.
Plastic frames have strongly been replacing metal-frames in consumer demand ... kind of like how semiauto pistols replaced revolvers in the same market.
More's the pity, though.
Just my thoughts, muddled as they may be.