Why aren't all CD players also DAC's?

Several years ago I had a California Audio Labs Tercet that was a one-box CD player but to use it as a CD player you installed the small RCA jumper from the coax "audio digital out" to the coax "audio digital in". In other words, the transport and the DAC parts of the machine were separated, so you could use it as either a DAC, transport, or regular CD player. That was prior to when the computer audio thing got big.

So my question is, with everyone nowadays having digital music on their computers and needing a DAC to play it through, why do manufacturers still make single-box CD players with no options for digital inputs? How much extra cost could it possibly add to allow that feature? That would certainly make the unit much more versatile.

Or am I just missing something?

I order to convert the digital recording which are 1's and 0's thus you must convert to analog which amp and the speakers they drive.
Note the quicker and most complete the conversion the better the sound Look at Meridian I beleive they are digital all the way though
Robertbrown, I'm not exactly sure I understand your statement.

My point is that a single-box CD player consists of both a transport and a DAC in the same box. Why haven't more manufacturers simply allowed access to these internal components via external connections, in a similar fashion to the decent amount of integrated amps having preouts?

I think they should too.
I can think of two reasons. First is cost for extra jacks and associated real estate on the chassis. There is also a downside in that the cable used to connect the transport section to the DAC section becomes a huge issue (check out threads here on digital cables).

The second reason is that an internal connection avoids the SPDIF conversion and associated clock recovery issues. With a direct on the board connection it's easy to keep separate clock and audio streams for reduced jitter (think I squared S).

CDPs are DACs. They're simply quite proprietary, decoding only those discs placed within them in predetermined formats, and not for outboard use... generally speaking.
Quite a few CDPs these days have digital inputs so that you can use the DAC portion of the player separately. Wadia had made this available for quite a while; looking quickly at a couple of websites, I see that Cambridge Audio has it on their top of the line 840 Azur, and the inexpensive Oppo has USB inputs. So I think manufacturers are getting the message.
Add the Marantz SA-15S2 and also most of Ayon's new line to a list of players with a digital input.
my aura note premier has a connection for ipod, but it uses cables instead of a direct interface. it also has a computer usb connection to play music right from your computer.
My Cary SACD has both transport and dac under one cover and you can use it as just a dac. Also the dac ins and outs are adjustable via the remote.
Ghostrider45, I can appreciate the downside of having the S/PDIF conversion, but I can't imagine that it adds too much cost in either money or performance. Besides, CD player mode would be unaffected, so what's the downside of offering a DAC input.

Based on your responses, there are a few more such players than I had anticipated, but there are still a very small minority of CD players that offer such option.

I truly feel that offering a Digital In option would make high-end CD players much more attractive.