Sounds like you've encountered a "sales-tech". They are often paid by commission, hence the push to sell upgrades and extras. As for ignitors, 175 ohms is a bit high but it's not an absolute indicator that it's going to fail. I'd consider replacing them or at least buying a couple of spares to have on hand in case they go out. As for the drain switches, if your units are installed in a finished area they should have some sort of emergency/overflow pan under them and a switch installed to detect if water starts flowing into that pan (indicating a leak). If you don't have this sort of safety on them, a leak could do a lot of damage before you catch it. If both of your units are installed in an unfinished basement (where a water backup isn't going to do damage) then you're probably fine without them if you're getting regular maintenance.
As for replacing a 10 year old system, that's (IMO) ridiculous if you're not having any problems. As long as you keep up with the maintenance, you should get plenty more years out of your system.
"We always fix it right the second time".
All posts are strictly my opinions and not those of my employer. I cannot make statements on behalf of my employer.
All advice posted by me is for educational purposes only, HVAC repairs should only be conducted by trained & qualified people.