The question isn't really so much "should there be more techs?" but rather "what would additional techs do?" Have they left anything out that really has to be there? I don't think any of the techs in Civ V are over-burdened with units/buildings/improvements/abilities, but until we get to play the game we can't really say.
I think the late game has a lot to be desired for unit selection and techs.
So much has changed between early industrial and modern times that I think that at least all the units listed should be included in the game:
Ironclad (slow, can't go out to ocean, and absolutely dominates the older Frigates)
Destroyer (WW2 level of tech, cheap, fast, can detect submarines and gets a bonus against them)
Submarine (WW2 level of sub/U-boat. Decent stealth, moves somewhat slowly, big bonus while attacking)
Aircraft Carrier (WW2 level of carrier, basic platform for aircraft launch)
Battleship (WW2 level, powerful in bombardment and direct combat but very expensive to build and maintain, so much so that it is arguable if it is worth the cost)
Cruiser (WW2 level of ship. Carries 2 aircraft. Better physical combat than the destroyer, but worse than a battleship. Does not detect subs, but moves somewhat quickly and can use it's AA to protect itself or ships 1 tile away from air attacks)
Missile Submarine or Nuclear Submarine (Modern level, can carry a couple tactical missiles (nuclear or cruise) and launch them. Same kind of attacking-bonus as the older submarine.
AEGIS Cruiser or Missile Cruiser (Modern level, can carry a couple tactical missiles, can defend against tactical missiles, AA attack, strongest direct/bombard naval unit in the game)
DDS Destroyer (Modern level anti-sub unit + direct/bombard unit. Cheaper than an AEGIS, but isn't quite as strong and lacks AA/Anti-missile defenses and cannot hold a tactical missile.
Supercarrier (Modern carrier, holds 3 aircraft and is large enough that although it does not have a good direct attack it takes quite a bit to sink. Has anti-missile defenses)
The current roster of naval units really doesn't give the feel of an "arms race". I mean, consider destroyers: You get the industrial-level tech to build them, you do so, and that is the highest tech of that type of ship you'll ever need. Ditto for aircraft carriers.
Outside of naval units, I think that leaving out UAV (Drone) aircraft is a mistake. "Bomber" type aircraft really went from standard Bombers in WW2 and ended up as UAVs due to cost (and other) reasons.
Also I don't think I've seen an ICBM yet. Atomic bomb, cruise missile, and nuclear missile are all good for missile weapons, but ICBM really needs to be included.