Here's some scenarios that show how JT is bad for established couples with children.
Jack & Jill own as JT, Jack dies, Jill inherits and goes into care, 100% of the value is counted for the care fees.
If they were TiC, Jack dies, leaves Jill a life interest in his share, Jill goes into care, only 50% is taken for her share, on Jills death Jacks share vests with the children.
Jack & Jill own as JT, Jill Dies, Jack inherits, Jack Re-marries and re-writes his will in favour of his new wife, Jack dies, everything follows Jacks new will
Jack & Jill own as JT, Jill dies, jack makes some bad decisions and runs into financial difficulties, the whole of the property is charged against and lost to creditors.
If they were TiC, as with care fees, Jills 50% that went into trust cannot be counted as jacks asset, his creditors can only charge his half.
JT is a great arrangement for a young couple, who have purchased together, don't have a family and may not have made wills as it automates the process - for couples looking to pass to the next generation in a guaranteed and tax efficient way JT is crazy bonkers, terrible idea.